You searched for subject:(Photophysics).
Showing records 1 – 30 of
193 total matches.
◁ [1] [2] [3] [4] [5] [6] [7] ▶
Victoria University of Wellington
1.
Gallaher, Joseph.
Spectroscopic investigation of excitonic and charge photogeneration processes in organic photovoltaic cells.
Degree: 2016, Victoria University of Wellington
URL: http://hdl.handle.net/10063/5251 
► Organic photovoltaic (OPV) cells show significant promise as a renewable energy resource capable of meeting the world’s large and growing energy needs. Increasing device efficiency…
(more)
▼ Organic photovoltaic (OPV) cells show significant promise as a renewable energy resource capable of meeting the world’s large and growing energy needs. Increasing device efficiency is central to achieving an economically viable option for widespread applications. To this end, a better understanding of the structure and dynamics of the electronic excited states is needed. In particular, the mechanism by which excitons (electron-hole pairs) escape their Coulombic attraction and generate photocurrent is yet to be established. In this thesis ultrafast laser spectroscopy, in particular transient absorption and time-resolved photoluminescence, are used to study: exciton relaxation, morphological effects on charge separation, and the pathway leading to triplet exciton states.
In Chapter 3, a series of oligothiophenes are synthesised with well-defined conjugation lengths to act as molecular models of polymer backbone sub-units, and thereby probe exciton relaxation processes. Time-resolved photoluminescence (TRPL) and transient absorption (TA) spectroscopy measurements presented in Chapter 4 reveal emission signatures evolve from a mirror image of absorption - which lacks vibronic structure - towards a spectrally narrower and vibronically structured species on the hundreds of femtosecond to early picosecond timescale. Analysis of this spectral evolution shows that a broad distribution of torsional conformers is driven to rapidly planarize in the excited state, including in solid films. This provides evidence that both torsional relaxation and energy migration could contribute to the non-mirror image absorption-emission spectra observed in polymer thin films.
Recently, long lived TA signatures have been attributed to triplet excited states with the suggested formation pathway being similar to organic light emitting diodes, whereby non-geminate (bimolecular) charge recombination leads to the formation of both singlet and triplet states. Isolated oligothiophenes in solution provide an ideal model system to investigate the role of structural relaxation on triplet exciton formation. Through analysis of TA spectral dynamics in Chapter 5, singlet and triplet exciton populations were tracked. Restriction of the torsional relaxation increased triplet yield suggesting vibrational hot states could drive triplet formation. This model could aid in understanding triplet exciton formation in polymer-based solar cells via spin-mixing instead of non-geminate recombination.
In a series of polymer:fullerene blends, the link between the nature of polymerfullerene intermixing and charge generation pathways was investigated. It is shown in Chapter 6 that free charge generation is most efficient in a 3-phase morphology that features intimately mixed polymer:fullerene regions amongst neat polymer and fullerene phases. Distinct spectroscopic signatures made it possible to determine whether holes occupy disordered or crystalline polymer chains. TA spectral dynamics reveal the migration of holes from intermixed to pure olymer regions in 3-phase…
Advisors/Committee Members: Hodgkiss, Justin.
Subjects/Keywords: Organic photovoltaics; Oligothiophenes; Polymer photophysics
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Gallaher, J. (2016). Spectroscopic investigation of excitonic and charge photogeneration processes in organic photovoltaic cells. (Doctoral Dissertation). Victoria University of Wellington. Retrieved from http://hdl.handle.net/10063/5251
Chicago Manual of Style (16th Edition):
Gallaher, Joseph. “Spectroscopic investigation of excitonic and charge photogeneration processes in organic photovoltaic cells.” 2016. Doctoral Dissertation, Victoria University of Wellington. Accessed April 23, 2021.
http://hdl.handle.net/10063/5251.
MLA Handbook (7th Edition):
Gallaher, Joseph. “Spectroscopic investigation of excitonic and charge photogeneration processes in organic photovoltaic cells.” 2016. Web. 23 Apr 2021.
Vancouver:
Gallaher J. Spectroscopic investigation of excitonic and charge photogeneration processes in organic photovoltaic cells. [Internet] [Doctoral dissertation]. Victoria University of Wellington; 2016. [cited 2021 Apr 23].
Available from: http://hdl.handle.net/10063/5251.
Council of Science Editors:
Gallaher J. Spectroscopic investigation of excitonic and charge photogeneration processes in organic photovoltaic cells. [Doctoral Dissertation]. Victoria University of Wellington; 2016. Available from: http://hdl.handle.net/10063/5251
University of Victoria
2.
Sheepwash, Molina Audrey Lorraine.
Synthesis, photophysics and photochemistry of substituted 2,7-Di-(t-butyl)-trans-10b,10c-dimethyl-10b,10c-dihydropyrenes.
Degree: Department of Chemistry, 2018, University of Victoria
URL: https://dspace.library.uvic.ca//handle/1828/10289
► The photochromism of several simple substituted and [e]-annelated 10b, 10c-dimethyl-10b, 10c-dihydropyrene derivatives was studied using steady state and time resolved fluorescence techniques as well as…
(more)
▼ The photochromism of several simple substituted and [e]-annelated 10b, 10c-dimethyl-10b, 10c-dihydropyrene derivatives was studied using steady state and time
resolved fluorescence techniques as well as chemical actinometry and laser flash
photolysis (LFP). The purpose of this study was to determine the mechanism of the
photoisomerization between the closed, coloured dimethyldihydropyrene isomer and the
open, colourless metacyclophanediene isomer. A detailed understanding of the switching
mechanism of such compounds will allow for the rational design of multichromophoric
switches in the future.
Fluorescence from the dimethyldihydropyrene isomers was weak (ɸ < 0.03). The
simple substituted systems exhibited sharp emissions comprised of a single transition
while the [e]-annelated derivatives emission were broader and resolved into two bands at
low temperature (77 K). The fluorescence lifetimes for the dimethyldihydropyrene
isomers were between 2.4 and 5.6 ns. The emission for the metacyclophanediene isomers
was found to be very structured with lifetimes between 12 and 17 ns for most derivatives.
The photoisomerization was found to proceed through the singlet excited state and
bond breakage / formation occurred on the nanosecond timescale as determined by LFP.
The triplet excited state, although formed, was not involved in the switching mechanism.
The ring opening isomerization quantum yields were found to be low for the simple
substituted systems (≤ 0.012) but were improved upon [e]-annelation (0.042 - 0.095).
The ring closing isomerization quantum yields for the annelated systems were found to be
much higher than the ring opening efficiencies (0.28 — 0.42) and were insensitive to
substitution or the nature of the fused arene moiety. Future synthesis and studies should
be based on the [e]-annelated architectures.
Advisors/Committee Members: Bohne, Cornelia (supervisor), Mitchell, Reginald H. (supervisor).
Subjects/Keywords: Photochemistry; Photophysics; Metacyclophanediene; Dimethyldihydropyrenes
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Sheepwash, M. A. L. (2018). Synthesis, photophysics and photochemistry of substituted 2,7-Di-(t-butyl)-trans-10b,10c-dimethyl-10b,10c-dihydropyrenes. (Thesis). University of Victoria. Retrieved from https://dspace.library.uvic.ca//handle/1828/10289
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Sheepwash, Molina Audrey Lorraine. “Synthesis, photophysics and photochemistry of substituted 2,7-Di-(t-butyl)-trans-10b,10c-dimethyl-10b,10c-dihydropyrenes.” 2018. Thesis, University of Victoria. Accessed April 23, 2021.
https://dspace.library.uvic.ca//handle/1828/10289.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Sheepwash, Molina Audrey Lorraine. “Synthesis, photophysics and photochemistry of substituted 2,7-Di-(t-butyl)-trans-10b,10c-dimethyl-10b,10c-dihydropyrenes.” 2018. Web. 23 Apr 2021.
Vancouver:
Sheepwash MAL. Synthesis, photophysics and photochemistry of substituted 2,7-Di-(t-butyl)-trans-10b,10c-dimethyl-10b,10c-dihydropyrenes. [Internet] [Thesis]. University of Victoria; 2018. [cited 2021 Apr 23].
Available from: https://dspace.library.uvic.ca//handle/1828/10289.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Sheepwash MAL. Synthesis, photophysics and photochemistry of substituted 2,7-Di-(t-butyl)-trans-10b,10c-dimethyl-10b,10c-dihydropyrenes. [Thesis]. University of Victoria; 2018. Available from: https://dspace.library.uvic.ca//handle/1828/10289
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
3.
Mcnamara, Louis Edward.
The Spectroscopic Characterization Of Newly Developed Emissive Materials And The Effects Of Environment On Their Photophysical Properties.
Degree: PhD, Chemistry and Biochemistry, 2015, University of Mississippi
URL: https://egrove.olemiss.edu/etd/420
► The development of new materials capable of efficient charge transfer and energy storage has become increasingly important in many areas of modern chemical research. This…
(more)
▼ The development of new materials capable of efficient charge transfer and energy storage has become increasingly important in many areas of modern chemical research. This is especially true for the development of emissive optoelectronic devices and in the field of solar to electric energy conversion. The characterization of the photophysical properties of new molecular systems for these applications has become critical in the design and development of these materials. Many molecular building blocks have been developed and understanding the properties of these molecules at a fundamental level is essential for their successful implementation and future engineering. This dissertation focuses on the characterization of some of these newly-developed molecular systems. The spectroscopic studies focus on the characterization of newly-developed molecules based on perylene and indolizine derivatives for solar to electric energy conversion, thienopyrazine derivatives for near infrared (NIR) emissive applications, an SCS pincer complex for blue emissive materials and a fluorescent probe for medical applications. The effects of noncovalent interactions are also investigated on these systems and a benchmark biological molecule trimethylamine N-oxide (TMAO).
Advisors/Committee Members: Nathan I. Hammer, Joseph R. Gladden, Steven Davis.
Subjects/Keywords: Characterization; Photophysics; Spectroscopy; Physical Chemistry
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Mcnamara, L. E. (2015). The Spectroscopic Characterization Of Newly Developed Emissive Materials And The Effects Of Environment On Their Photophysical Properties. (Doctoral Dissertation). University of Mississippi. Retrieved from https://egrove.olemiss.edu/etd/420
Chicago Manual of Style (16th Edition):
Mcnamara, Louis Edward. “The Spectroscopic Characterization Of Newly Developed Emissive Materials And The Effects Of Environment On Their Photophysical Properties.” 2015. Doctoral Dissertation, University of Mississippi. Accessed April 23, 2021.
https://egrove.olemiss.edu/etd/420.
MLA Handbook (7th Edition):
Mcnamara, Louis Edward. “The Spectroscopic Characterization Of Newly Developed Emissive Materials And The Effects Of Environment On Their Photophysical Properties.” 2015. Web. 23 Apr 2021.
Vancouver:
Mcnamara LE. The Spectroscopic Characterization Of Newly Developed Emissive Materials And The Effects Of Environment On Their Photophysical Properties. [Internet] [Doctoral dissertation]. University of Mississippi; 2015. [cited 2021 Apr 23].
Available from: https://egrove.olemiss.edu/etd/420.
Council of Science Editors:
Mcnamara LE. The Spectroscopic Characterization Of Newly Developed Emissive Materials And The Effects Of Environment On Their Photophysical Properties. [Doctoral Dissertation]. University of Mississippi; 2015. Available from: https://egrove.olemiss.edu/etd/420
University of Minnesota
4.
Hinkle, Lindsay Marie.
Crystalline transition metal-based sensors for the optical detection of oxygen.
Degree: PhD, Chemistry, 2012, University of Minnesota
URL: http://purl.umn.edu/158333
► Oxygen is essential to life, motivating the development of optical oxygen sensors. Current sensing methods rely on either electrochemical measurements or an optical response from…
(more)
▼ Oxygen is essential to life, motivating the development of optical oxygen sensors. Current sensing methods rely on either electrochemical measurements or an optical response from solutions or polymer based materials. These techniques often suffer from support degradation, oxygen consumption, and response plots that are difficult to interpret. A promising alternative to current optical sensing technologies are porous crystalline solids, as these solids provide a consistent emission site along with the necessary open space to facilitate diffusion of molecular oxygen through the material. This thesis explores neutral, mono-, di-, and tricationic coordination complexes for use as solid-state devices to detect oxygen. This series of transition metal complexes was synthesized, and the packing motifs studied by single crystal X-ray diffraction. After investigating the crystalline packing, photophysical properties, and sensitivity of emission toward oxygen, it was determined that the mono- and dicationic complexes are the most promising materials based on their sensitivity and long term stability. In Chapter 1, a brief introduction to oxygen sensing and the goals of this project are given. In Chapter 2, the synthesis and characterization of a series of neutral zinc(II) compounds are reported. One specific compound, Zn(terpy-*)Br2 (where terpy-* = 4,4',4''-tri-tert-butyl-2,2':6',2''-terpyridine) showed promise for detecting small oxygen concentrations. However, stability testing determined the compound was not stable toward LED illumination and oxygen exposure.
In Chapter 3, a monocationic family of compounds based on the [Cu(P^P)(N^N)]+ core (where P^P is a bidentate phosphine and N^N is a bidentate amine) was explored. After the sensing ability of the compounds was determined, their stability was rigorously tested. The studies demonstrate that compounds with tfpb- (where tfpb- = tetrakis[bis-3,5-trifluoromethyl(phenylborate)]) counterions were typically more stable and more sensitive to changes in oxygen than their BF4- and pfpb- (pfpb- = tetrakis-(pentafluorophenyl)borate) counterparts. Additionally, a mechanism for the degradation of these sensors is proposed.
In Chapter 4, a zinc(II) dicationic polypyridine complex was tested and compared to a previously reported and analogous ruthenium(II) compound. Based on the knowledge that similarly shaped molecules tend to pack in a similar way, it was hypothesized that crystalline materials of both the Ru(II) and Zn(II) compounds would pack similarly and therefore sense oxygen in a similar manner. Even though the compounds crystallize in a similar manner and the trends in oxygen sensitivity are the same, the KSV parameters were not as similar as was predicted. The difference in sensing ability is due to a different quenching mechanism in the Ru(II) and Zn(II) complexes. Nonetheless, the Zn(II) family of compounds is a reliable and…
Subjects/Keywords: Crystallography; Oxygen detection; Photophysics
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Hinkle, L. M. (2012). Crystalline transition metal-based sensors for the optical detection of oxygen. (Doctoral Dissertation). University of Minnesota. Retrieved from http://purl.umn.edu/158333
Chicago Manual of Style (16th Edition):
Hinkle, Lindsay Marie. “Crystalline transition metal-based sensors for the optical detection of oxygen.” 2012. Doctoral Dissertation, University of Minnesota. Accessed April 23, 2021.
http://purl.umn.edu/158333.
MLA Handbook (7th Edition):
Hinkle, Lindsay Marie. “Crystalline transition metal-based sensors for the optical detection of oxygen.” 2012. Web. 23 Apr 2021.
Vancouver:
Hinkle LM. Crystalline transition metal-based sensors for the optical detection of oxygen. [Internet] [Doctoral dissertation]. University of Minnesota; 2012. [cited 2021 Apr 23].
Available from: http://purl.umn.edu/158333.
Council of Science Editors:
Hinkle LM. Crystalline transition metal-based sensors for the optical detection of oxygen. [Doctoral Dissertation]. University of Minnesota; 2012. Available from: http://purl.umn.edu/158333
University of Cambridge
5.
Feng, Jiale.
Triplet exciton management via solid-state interactions in organic semiconductors.
Degree: PhD, 2020, University of Cambridge
URL: https://doi.org/10.17863/CAM.58156
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.818117
► Tightly-bound excitons play an important role in the function of molecular materials for light emission and light harvesting. This thesis investigates the effects of solid-state…
(more)
▼ Tightly-bound excitons play an important role in the function of molecular materials for light emission and light harvesting. This thesis investigates the effects of solid-state interactions on triplet excitons in a new family of organometallic light emitters, carbene-metal-amides (CMAs). Triplet excitons are normally silent in luminescence due to the spin-forbidden decay process, whereas effectively harvesting triplet excitons helps to boost the performance of light-emitting devices. As the triplet excitons are sensitive to both molecular properties and external environment, in this thesis we deploy optical spectroscopy techniques to understand the effect of solid-state interactions on triplet excitons. After introducing the relevant theoretical and experimental background of triplet formation in a single molecule and interactions between molecules, we firstly describe the intermolecular electrostatic interactions and the role of triplet diffusion and find that the combined effects of both blueshift the charge-transfer energy while other photophysical properties remain relatively constant in gold-bridged CMA1. We then describe the crystallisation of CMA1 thin films, which allows us to experimentally investigate the link between molecular conformations and photophysical properties. A combination of restricted torsional distortion and molecular electronic polarisation greatly blueshifts the charge-transfer emission by around 400 meV in the crystalline versus the amorphous phase. We also discover that the intersystem crossing rate and emission kinetics are unaffected by the extent of torsional distortion. Finally, we apply electrostatic interactions to the other two coinage metal-bridged CMAs to explore the effect of heavy metal atoms on the intersystem crossing and luminescence mechanism. We show that the photophysical properties do not reflect expected trends based upon the heavy atom effect as both direct coupling between charge-transfers states and spin-vibronic coupling via an intermediate state are present.
Subjects/Keywords: photophysics; optoelectronics; organic semiconductors
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Feng, J. (2020). Triplet exciton management via solid-state interactions in organic semiconductors. (Doctoral Dissertation). University of Cambridge. Retrieved from https://doi.org/10.17863/CAM.58156 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.818117
Chicago Manual of Style (16th Edition):
Feng, Jiale. “Triplet exciton management via solid-state interactions in organic semiconductors.” 2020. Doctoral Dissertation, University of Cambridge. Accessed April 23, 2021.
https://doi.org/10.17863/CAM.58156 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.818117.
MLA Handbook (7th Edition):
Feng, Jiale. “Triplet exciton management via solid-state interactions in organic semiconductors.” 2020. Web. 23 Apr 2021.
Vancouver:
Feng J. Triplet exciton management via solid-state interactions in organic semiconductors. [Internet] [Doctoral dissertation]. University of Cambridge; 2020. [cited 2021 Apr 23].
Available from: https://doi.org/10.17863/CAM.58156 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.818117.
Council of Science Editors:
Feng J. Triplet exciton management via solid-state interactions in organic semiconductors. [Doctoral Dissertation]. University of Cambridge; 2020. Available from: https://doi.org/10.17863/CAM.58156 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.818117
King Abdullah University of Science and Technology
6.
Dursun, Ibrahim.
Engineering of Photophysical Properties in Halide Perovskites: From Nano to Bulk for Optoelectronic Applications.
Degree: Physical Science and Engineering (PSE) Division, 2019, King Abdullah University of Science and Technology
URL: http://hdl.handle.net/10754/652927
► Halide perovskites have attracted the attention of a broad segment of the optoelectronics field, owing to their outstanding optical and electrical properties; simple low-temperature solution…
(more)
▼ Halide perovskites have attracted the attention of a broad segment of the optoelectronics field, owing to their outstanding optical and electrical properties; simple low-temperature solution processing; low-cost raw materials; and tunable bandgaps. The main objective of this dissertation is engineering the materials’ properties of halide perovskites – their crystallinity, composition, and dimensionality – in order to understand the fundamental photophysical processes leading to their extraordinary behavior and to translate this understanding into optoelectronic applications. This dissertation is divided into two parts: the first focuses primarily on halide perovskites as a photonic source from an emission perspective, whereas the second is devoted to fundamental investigation of emergent photophysical concepts in halide perovskite materials including photon recycling and hot carriers.
In the first part of this dissertation, we studied the synthesis and characterization of Cs-Pb-Br-based perovskite-related single crystals to elucidate the origin of the materials’ emission properties. After that, we presented perovskite nanocrystals (NCs) as a color converter in solid state lighting and visible light communication. Perovskites NCs’ converted white light (with a high color rendering index of 89 and a color correlated temperature of 3236 K) exhibits an extraordinary modulation bandwidth of 491 MHz, and data transmission rate of 2 Gbit/s.
In the second part of this dissertation, we developed a facile synthesis method for perovskite microwires and demonstrate efficient photon recycling in those microwires with conclusive spectroscopic evidence. Subsequently, we investigated hot charge carriers in halide perovskites solar cells by a combination of laser spectroscopy and density functional modelling. Furthermore, we presented that hot holes were extracted at the device interface between the perovskite absorber and a hole transport layer.
The findings and methodologies described in this dissertation represent a significant advance for utilizing the optical properties of halide perovskites, bring new fundamental photophysical insights to the field of halide perovskites, and provide a new powerful approach for designing the interface of perovskite solar cells to efficiently extract the hot charge carriers.
Advisors/Committee Members: Bakr, Osman (advisor), Mohammed, Omar F. (committee member), Alshareef, Husam N. (committee member), Malko, Anton (committee member).
Subjects/Keywords: Halide perovskites; Photophysics; Optoelectronic
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Dursun, I. (2019). Engineering of Photophysical Properties in Halide Perovskites: From Nano to Bulk for Optoelectronic Applications. (Thesis). King Abdullah University of Science and Technology. Retrieved from http://hdl.handle.net/10754/652927
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Dursun, Ibrahim. “Engineering of Photophysical Properties in Halide Perovskites: From Nano to Bulk for Optoelectronic Applications.” 2019. Thesis, King Abdullah University of Science and Technology. Accessed April 23, 2021.
http://hdl.handle.net/10754/652927.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Dursun, Ibrahim. “Engineering of Photophysical Properties in Halide Perovskites: From Nano to Bulk for Optoelectronic Applications.” 2019. Web. 23 Apr 2021.
Vancouver:
Dursun I. Engineering of Photophysical Properties in Halide Perovskites: From Nano to Bulk for Optoelectronic Applications. [Internet] [Thesis]. King Abdullah University of Science and Technology; 2019. [cited 2021 Apr 23].
Available from: http://hdl.handle.net/10754/652927.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Dursun I. Engineering of Photophysical Properties in Halide Perovskites: From Nano to Bulk for Optoelectronic Applications. [Thesis]. King Abdullah University of Science and Technology; 2019. Available from: http://hdl.handle.net/10754/652927
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Cambridge
7.
Feng, Jiale.
Triplet Exciton Management via Solid-State Interactions in Organic Semiconductors.
Degree: PhD, 2020, University of Cambridge
URL: https://www.repository.cam.ac.uk/handle/1810/311065
► Tightly-bound excitons play an important role in the function of molecular materials for light emission and light harvesting. This thesis investigates the effects of solid-state…
(more)
▼ Tightly-bound excitons play an important role in the function of molecular materials for light emission and light harvesting. This thesis investigates the effects of solid-state interactions on triplet excitons in a new family of organometallic light emitters, carbene-metal-amides (CMAs). Triplet excitons are normally silent in luminescence due to the spin-forbidden decay process, whereas effectively harvesting triplet excitons helps to boost the performance of light-emitting devices. As the triplet excitons are sensitive to both molecular properties and external environment, in this thesis we deploy optical spectroscopy techniques to understand the effect of solid-state interactions on triplet excitons. After introducing the relevant theoretical and experimental background of triplet formation in a single molecule and interactions between molecules, we firstly describe the intermolecular electrostatic interactions and the role of triplet diffusion and find that the combined effects of both blueshift the charge-transfer energy while other photophysical properties remain relatively constant in gold-bridged CMA1. We then describe the crystallisation of CMA1 thin films, which allows us to experimentally investigate the link between molecular conformations and photophysical properties. A combination of restricted torsional distortion and molecular electronic polarisation greatly blueshifts the charge-transfer emission by around 400 meV in the crystalline versus the amorphous phase. We also discover that the intersystem crossing rate and emission kinetics are unaffected by the extent of torsional distortion. Finally, we apply electrostatic interactions to the other two coinage metal-bridged CMAs to explore the effect of heavy metal atoms on the intersystem crossing and luminescence mechanism. We show that the photophysical properties do not reflect expected trends based upon the heavy atom effect as both direct coupling between charge-transfers states and spin-vibronic coupling via an intermediate state are present.
Subjects/Keywords: photophysics; optoelectronics; organic semiconductors
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Feng, J. (2020). Triplet Exciton Management via Solid-State Interactions in Organic Semiconductors. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/311065
Chicago Manual of Style (16th Edition):
Feng, Jiale. “Triplet Exciton Management via Solid-State Interactions in Organic Semiconductors.” 2020. Doctoral Dissertation, University of Cambridge. Accessed April 23, 2021.
https://www.repository.cam.ac.uk/handle/1810/311065.
MLA Handbook (7th Edition):
Feng, Jiale. “Triplet Exciton Management via Solid-State Interactions in Organic Semiconductors.” 2020. Web. 23 Apr 2021.
Vancouver:
Feng J. Triplet Exciton Management via Solid-State Interactions in Organic Semiconductors. [Internet] [Doctoral dissertation]. University of Cambridge; 2020. [cited 2021 Apr 23].
Available from: https://www.repository.cam.ac.uk/handle/1810/311065.
Council of Science Editors:
Feng J. Triplet Exciton Management via Solid-State Interactions in Organic Semiconductors. [Doctoral Dissertation]. University of Cambridge; 2020. Available from: https://www.repository.cam.ac.uk/handle/1810/311065
University of Cambridge
8.
Jones, Saul.
Photophysics of small molecule organo-metallic complexes for OLED applications.
Degree: 2019, University of Cambridge
URL: https://www.repository.cam.ac.uk/handle/1810/319140
► Over the last 3 decades, advances in chemistry have produced new semiconducting materials with very different properties, transitioning from inorganic to organic semiconductors, allowing previous…
(more)
▼ Over the last 3 decades, advances in chemistry have produced new semiconducting materials with very different properties, transitioning from inorganic to organic semiconductors, allowing previous material constraints to be worked around. Organic semiconductors can be transparent, flexible, and soluble and are able to be tuned to absorb or emit across a wide range of wavelengths. This has revolutionised device technology, already competing in global lighting and display industries. Whilst organic semiconductors avoid some of the problems inherent in inorganic technologies, they have their own limitations. The electronic transitions in organic materials are highly spin sensitive, as excitons form due to lower dipole moments. Triplet excitons cannot directly couple radiatively to the ground state, so unless additional processes to alter spin angular momentum exist 75% of excitations formed cannot emit light. I have studied a new class of small molecules, Carbene Metal Amides (CMAs) which display efficient emission, and have been used in OLEDs, breaking the efficiency records for both solution processed devices (27.5%), and evaporated host free emissive layers (23%). Herein I present my work using a variety of time resolved spectroscopic techniques to study the photophysical properties this new class of emitters, explaining the rapid and efficient excited state spin conversion, and the effects of molecular modification. I show that this class of emitter sits between two existing technologies for emission from triplet states, namely heavy metal phosphorescence and organic Thermally Activated Delayed Fluorescence (TADF). The incorporation of both sets of physical processes which have previously allowed emission from triplet states has resulted in a class of materials with near 100% photoluminescence and internal device efficiencies, and I show the nature of the states involved in the emission process, how they respond to a number of modifications to the molecular structure, and discuss how this class of materials may be further developed for device applications.
Subjects/Keywords: OLED; TADF; CMA; photophysics
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Jones, S. (2019). Photophysics of small molecule organo-metallic complexes for OLED applications. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/319140
Chicago Manual of Style (16th Edition):
Jones, Saul. “Photophysics of small molecule organo-metallic complexes for OLED applications.” 2019. Doctoral Dissertation, University of Cambridge. Accessed April 23, 2021.
https://www.repository.cam.ac.uk/handle/1810/319140.
MLA Handbook (7th Edition):
Jones, Saul. “Photophysics of small molecule organo-metallic complexes for OLED applications.” 2019. Web. 23 Apr 2021.
Vancouver:
Jones S. Photophysics of small molecule organo-metallic complexes for OLED applications. [Internet] [Doctoral dissertation]. University of Cambridge; 2019. [cited 2021 Apr 23].
Available from: https://www.repository.cam.ac.uk/handle/1810/319140.
Council of Science Editors:
Jones S. Photophysics of small molecule organo-metallic complexes for OLED applications. [Doctoral Dissertation]. University of Cambridge; 2019. Available from: https://www.repository.cam.ac.uk/handle/1810/319140
University of California – Berkeley
9.
Lewis, Nicholas Henry Cohen.
Two-Dimensional Electronic-Vibrational Spectroscopy.
Degree: Chemistry, 2016, University of California – Berkeley
URL: http://www.escholarship.org/uc/item/3np6394x
► This dissertation describes the development and initial applications of Two-Dimensional Electronic-Vibrational spectroscopy (2DEV), a multidimensional ultrafast spectroscopic technique that is capable of directly probing the…
(more)
▼ This dissertation describes the development and initial applications of Two-Dimensional Electronic-Vibrational spectroscopy (2DEV), a multidimensional ultrafast spectroscopic technique that is capable of directly probing the coupling between electronic and vibrational transitions in molecular species.This thesis first provides the necessary background and motivation driving the development of this spectroscopy, discussing the role of electronic-vibrational coupling in small molecule photophysics and the ways we can take advantage of these physics to study electronic excitation transfer in photosynthetic light harvesting systems. It then discusses the details of the apparatus constructed to perform the 2DEV experiments, as well as some of the important aspects of the signal processing and extraction of the desired signal, using phase cycling techniques. It goes on to describe the development of a simple model to be used in understanding the new information content accessible with 2DEV, and presents experimental results from the laser dye DTTCI. The basic predictions of the model, such as the dynamics of the spectral lineshape, are shown to hold in these experimental results, and we provide an experimental measurement for the difference in the strength of the vibration-bath coupling between the electronic ground and excited states.In chapter 4, the model is extended to the case of an electronically coupled dimer, and a method is proposed by which 2DEV could potentially be used to study the movement of electronic excitations through a molecular aggregate, such as a photosynthetic light harvesting complex. It is shown how it might be possible to measure the electronic excited state populations directly in the site basis, without the need for an accompanying model. To demonstrate an experimental implementation of this method, the 2DEV spectra of Chlorophyll a and b in solution are then presented, assigning the important spectral features and demonstrating conclusively the connection between spectral shifts along the electronic and vibrational axes due to changes in the axial coordination state of the central Mg. This is a first step which is then expanded upon with the demonstration of the experimental application of 2DEV to the major light harvesting complex in plants, LHCII, and an illustration that the technique proposed in chapter 4 is technically sound. Indications are observed of long lived population of Chl b which contradicts the predictions of current models for the excitonic structure of this system, and calls into question our current understanding of the initial energy transfer dynamics in plant photosynthesis.Finally, a discussion is provided of some of the promising directions for 2DEV to be further developed in the future.
Subjects/Keywords: Chemistry; Physical chemistry; Photophysics; Photosynthesis; Spectroscopy
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Lewis, N. H. C. (2016). Two-Dimensional Electronic-Vibrational Spectroscopy. (Thesis). University of California – Berkeley. Retrieved from http://www.escholarship.org/uc/item/3np6394x
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Lewis, Nicholas Henry Cohen. “Two-Dimensional Electronic-Vibrational Spectroscopy.” 2016. Thesis, University of California – Berkeley. Accessed April 23, 2021.
http://www.escholarship.org/uc/item/3np6394x.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Lewis, Nicholas Henry Cohen. “Two-Dimensional Electronic-Vibrational Spectroscopy.” 2016. Web. 23 Apr 2021.
Vancouver:
Lewis NHC. Two-Dimensional Electronic-Vibrational Spectroscopy. [Internet] [Thesis]. University of California – Berkeley; 2016. [cited 2021 Apr 23].
Available from: http://www.escholarship.org/uc/item/3np6394x.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Lewis NHC. Two-Dimensional Electronic-Vibrational Spectroscopy. [Thesis]. University of California – Berkeley; 2016. Available from: http://www.escholarship.org/uc/item/3np6394x
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Temple University
10.
Spata, Vincent Anthony.
PHOTOINITIATED-PROCESSES IN ADENINE OLIGONUCLEOTIDES: EXAMINING THE NATURE OF π-STACKING INTERACTIONS IN MULTI-CHROMOPHORE SYSTEMS.
Degree: PhD, 2016, Temple University
URL: http://digital.library.temple.edu/u?/p245801coll10,388262
► Chemistry
DNA provides the genetic code which is almost universal in all living organisms. When DNA is exposed to ultra-violet light it can cause cell…
(more)
▼ Chemistry
DNA provides the genetic code which is almost universal in all living organisms. When DNA is exposed to ultra-violet light it can cause cell degradation and mutation which are two of the major causes which lead to cancer. The nature of decay in DNA oligomers is a widely studied topic. Fluorescence and Transient Absorption (TA) experiments on polynucleotides which compare the behavior of the decay to the monomer bases have revealed the presence of longer-lived components in the multimeric systems. There has been heated debate over the character of the excited states responsible for the long-lived signals. Theoretical methods are well suited to compliment experiment by providing a description of processes and physical properties on the molecular level. We have studied π-stacked adenines in the gas-phase with Quantum Mechanical (QM) methods, but also in the helical environment using high-level ab initio methods, classical simulations and the combination of the two (QM/MM). Inclusion of the environmental interactions dramatically alters the shape of the potential energy surfaces due to steric interactions from the backbone and interactions with the surrounding bases and environment. This work examines the complete picture of photophysical processes occurring in adenine oligonucleotides within the helical environment after the absorption of a photon: the nature of initial absorption and the subsequent radiative and non-radiative decay pathways. It contributes key discoveries inherent to the mechanisms which govern photo-initiated processes in DNA, and also contributes to our fundamental knowledge of the photophysical behavior of π-stacked chromophores. The work reveals the effects of π-stacking interactions and the environment on photo-initiated processes in oligonucleotides. It reveals that excitonic coupling is responsible for the key differences in features in the absorption spectrum of adenine oligomers compared to the isolated bases, illustrates the role of charge transfer (CT) mixing in both absorption and decay processes, and the importance of bonded excimers in deactivation. The work also illustrates that CT excimers are responsible for the long-lived signals evidenced in Transient Absorption and Fluorescence experiments and that neutral excimers can exist within the DNA helical environment. It also adds to the discussion in the field on the nature of photodecay mechanisms occurring within the DNA helix.
Temple University – Theses
Advisors/Committee Members: Matsika, Spiridoula;, Spano, Francis C., Stanley, Robert J., Perdew, John P.;.
Subjects/Keywords: Physical chemistry;
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Spata, V. A. (2016). PHOTOINITIATED-PROCESSES IN ADENINE OLIGONUCLEOTIDES: EXAMINING THE NATURE OF π-STACKING INTERACTIONS IN MULTI-CHROMOPHORE SYSTEMS. (Doctoral Dissertation). Temple University. Retrieved from http://digital.library.temple.edu/u?/p245801coll10,388262
Chicago Manual of Style (16th Edition):
Spata, Vincent Anthony. “PHOTOINITIATED-PROCESSES IN ADENINE OLIGONUCLEOTIDES: EXAMINING THE NATURE OF π-STACKING INTERACTIONS IN MULTI-CHROMOPHORE SYSTEMS.” 2016. Doctoral Dissertation, Temple University. Accessed April 23, 2021.
http://digital.library.temple.edu/u?/p245801coll10,388262.
MLA Handbook (7th Edition):
Spata, Vincent Anthony. “PHOTOINITIATED-PROCESSES IN ADENINE OLIGONUCLEOTIDES: EXAMINING THE NATURE OF π-STACKING INTERACTIONS IN MULTI-CHROMOPHORE SYSTEMS.” 2016. Web. 23 Apr 2021.
Vancouver:
Spata VA. PHOTOINITIATED-PROCESSES IN ADENINE OLIGONUCLEOTIDES: EXAMINING THE NATURE OF π-STACKING INTERACTIONS IN MULTI-CHROMOPHORE SYSTEMS. [Internet] [Doctoral dissertation]. Temple University; 2016. [cited 2021 Apr 23].
Available from: http://digital.library.temple.edu/u?/p245801coll10,388262.
Council of Science Editors:
Spata VA. PHOTOINITIATED-PROCESSES IN ADENINE OLIGONUCLEOTIDES: EXAMINING THE NATURE OF π-STACKING INTERACTIONS IN MULTI-CHROMOPHORE SYSTEMS. [Doctoral Dissertation]. Temple University; 2016. Available from: http://digital.library.temple.edu/u?/p245801coll10,388262
Princeton University
11.
Taffet, Elliot.
Unmasking Underlying Molecular Photophysical Mechanisms Using Quantum Chemistry
.
Degree: PhD, 2019, Princeton University
URL: http://arks.princeton.edu/ark:/88435/dsp017w62fc131
► Quantum chemistry is performed on biological chromophores in light harvesting and synthetic chromophores in targeted photochemical applications to elucidate how molecular electronic structure impacts their…
(more)
▼ Quantum chemistry is performed on biological chromophores in light harvesting and synthetic chromophores in targeted photochemical applications to elucidate how molecular electronic structure impacts their underlying function. This function is revealed to manifest from the interplay between light-absorbing bright states and light- transmitting dark electronic excited states. The role played by these states, representing either different spatial or different spin symmetries, is discerned using multireference perturbation theory methodologies. Through these methods, molecular mechanisms of spin manipulation underlying the photophysical complexity observed in experimental spectroscopy are unveiled. These mechanisms hinge on correlations entangling pairs of spin-triplet eigenfunctions or spin-orbit coupling connecting formally spin singlet and spin triplet states. The former is unveiled to be the key intermediate initiator for multiplying molecular charge production from light, while the latter is unveiled to be the key driving force for multiplying light production from charges initiated by electrical stimulation. These processes are simulated at the molecular level using nonadiabatic dynamics that tracks electronic population transfer between states driven by nuclear motion in time. The dynamics are directed by couplings that may be modulated through definable nuclear distortion traceable to the activation of specific vibrational degrees of freedom. These computed vibrationally-assisted electronic dynamics across model molecular systems enable the discrimination between intrinsic intramolecular
photophysics and the effects of the surrounding molecular environment in naturally- occurring supramolecular pigment-protein complexes or device active layers.
Advisors/Committee Members: Scholes, Gregory D (advisor).
Subjects/Keywords: exchange;
fission;
fluorescence;
multireference;
photophysics;
spectroscopy
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Taffet, E. (2019). Unmasking Underlying Molecular Photophysical Mechanisms Using Quantum Chemistry
. (Doctoral Dissertation). Princeton University. Retrieved from http://arks.princeton.edu/ark:/88435/dsp017w62fc131
Chicago Manual of Style (16th Edition):
Taffet, Elliot. “Unmasking Underlying Molecular Photophysical Mechanisms Using Quantum Chemistry
.” 2019. Doctoral Dissertation, Princeton University. Accessed April 23, 2021.
http://arks.princeton.edu/ark:/88435/dsp017w62fc131.
MLA Handbook (7th Edition):
Taffet, Elliot. “Unmasking Underlying Molecular Photophysical Mechanisms Using Quantum Chemistry
.” 2019. Web. 23 Apr 2021.
Vancouver:
Taffet E. Unmasking Underlying Molecular Photophysical Mechanisms Using Quantum Chemistry
. [Internet] [Doctoral dissertation]. Princeton University; 2019. [cited 2021 Apr 23].
Available from: http://arks.princeton.edu/ark:/88435/dsp017w62fc131.
Council of Science Editors:
Taffet E. Unmasking Underlying Molecular Photophysical Mechanisms Using Quantum Chemistry
. [Doctoral Dissertation]. Princeton University; 2019. Available from: http://arks.princeton.edu/ark:/88435/dsp017w62fc131
University of North Texas
12.
Determan, John J.
Photophysics and Photochemistry of Copper(I) Phosphine and Collidine Complexes: An Experimental/Theoretical Investigation.
Degree: 2011, University of North Texas
URL: https://digital.library.unt.edu/ark:/67531/metadc84199/
► Copper(I) complexes have been studied through both experimental and computational means in the presented work. Overall, the work focuses on photophysical and photochemical properties of…
(more)
▼ Copper(I) complexes have been studied through both experimental and computational means in the presented work. Overall, the work focuses on photophysical and photochemical properties of copper(I) complexes. Photophysical and photochemical properties are found to be dependent on the geometries of the copper(I) complexes. One of the geometric properties that are important for both photochemical and photophysical properties is coordination number. Coordination numbers have been observed to be dependent on both ligand size and recrystallization conditions. The complexes geometric structure, as well as the electronic effects of the coordination ligands, is shown both computationally as well as experimentally to affect the emission energies. Two-coordinate complexes are seen to have only weak emission at liquid nitrogen temperature (77 K), while at room temperature (298 K) the two-coordinate complexes are not observed to be luminescent. Three-coordinate complexes are observed to be luminescent at liquid nitrogen temperature as well as at room temperature. The three-coordinate complexes have a Y-shaped ground (S0) state that distorts towards a T-shape upon photoexcitation to the lowest lying phosphorescent state (T1). The geometric distortion is tunable by size of the coordinating ligand. Luminescence is controllable by limiting the amount of non-radiative emission. One manner by which non-radiative emission is controlled is the amount of geometric distortion that occurs as the complex undergoes photoexcitation. Bulky ligands allow for less distortion than smaller ligands, leading to higher emission energies (blue shifted energies) with higher quantum efficiency. Tuning emission and increasing quantum efficiencies can be used to create highly efficient, white emitting materials for use in white OLEDS.
Advisors/Committee Members: Omary, Mohammad A., Cundari, Thomas R., Richmond, Michael G., Wilson, Angela K..
Subjects/Keywords: Copper(I) complexes; OLED; luminescence; photochemistry; photophysics
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
University of Oxford
13.
Gryte, Kristofer.
Analysis methods for single molecule fluorescence spectroscopy.
Degree: PhD, 2012, University of Oxford
URL: http://ora.ox.ac.uk/objects/uuid:148969c6-78aa-49c2-8f0e-2d5e5018fd98
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.581115
► This thesis describes signal analysis methods for single-molecule fluorescence data. The primary factor motivating method development is the need to distinguish single-molecule FRET fluctuations due…
(more)
▼ This thesis describes signal analysis methods for single-molecule fluorescence data. The primary factor motivating method development is the need to distinguish single-molecule FRET fluctuations due to conformational dynamics from fluctuations due to distance-independent FRET changes. Single-molecule Förster resonance energy transfer (FRET) promises a distinct advantage compared to alternative biochemical methods in its potential to relate biomolecular structure to function. Standard measurements assume that the mean transfer efficiency between two fluorescent probes, a donor and an acceptor, corresponds to the mean donor-acceptor distance, thus providing structural information. Accordingly, measurement analysis assumes that mean transfer efficiency fluctuations entail mean donor-acceptor distance fluctuations. Detecting such fluctuations is important in resolving molecular dynamics, as molecular function often necessitates structural changes. A problem arises, however, in that factors other than donor-acceptor distance changes may induce mean transfer efficiency fluctuations. We refer to these factors as distance-independent FRET changes. We present analysis methods to detect distance-independent photophysical dynamics and to determine their correlation with distance-dependent FRET dynamics. First, we review a theory of photon statistics and show how we can use the theory to detect FRET fluctuations. Second, we extend the theory to alternating laser excitation (ALEx) measurements and demonstrate how fluorophore stoichiometry, a measure of fluorophore brightness, reports on distance-independent photophysical dynamics. Next, we provide a measure to determine the extent to which stoichiometry fluctuations account for FRET dynamics. Finally, we use a framework similar to the preceding along with recent advances in the theory of total internal reflection fluorescence (TIRF) microscopy FRET measurements to detect TIRF FRET fluctuations which occur on a timescale faster than the measurement temporal resolution. We validate our methods with simulations and demonstrate their utility in delineating RNA polymerase open complex conformational dynamics.
Subjects/Keywords: 543.56; Biophysics; Time-Series Analysis; confocal; Photophysics
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Gryte, K. (2012). Analysis methods for single molecule fluorescence spectroscopy. (Doctoral Dissertation). University of Oxford. Retrieved from http://ora.ox.ac.uk/objects/uuid:148969c6-78aa-49c2-8f0e-2d5e5018fd98 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.581115
Chicago Manual of Style (16th Edition):
Gryte, Kristofer. “Analysis methods for single molecule fluorescence spectroscopy.” 2012. Doctoral Dissertation, University of Oxford. Accessed April 23, 2021.
http://ora.ox.ac.uk/objects/uuid:148969c6-78aa-49c2-8f0e-2d5e5018fd98 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.581115.
MLA Handbook (7th Edition):
Gryte, Kristofer. “Analysis methods for single molecule fluorescence spectroscopy.” 2012. Web. 23 Apr 2021.
Vancouver:
Gryte K. Analysis methods for single molecule fluorescence spectroscopy. [Internet] [Doctoral dissertation]. University of Oxford; 2012. [cited 2021 Apr 23].
Available from: http://ora.ox.ac.uk/objects/uuid:148969c6-78aa-49c2-8f0e-2d5e5018fd98 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.581115.
Council of Science Editors:
Gryte K. Analysis methods for single molecule fluorescence spectroscopy. [Doctoral Dissertation]. University of Oxford; 2012. Available from: http://ora.ox.ac.uk/objects/uuid:148969c6-78aa-49c2-8f0e-2d5e5018fd98 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.581115
14.
Brenda Gomes Fanchiotti.
Estudo da estabilidade da curcumina em quitosanas comercial e anfifílica.
Degree: 2019, University of São Paulo
URL: http://www.teses.usp.br/teses/disponiveis/75/75134/tde-05062019-134029/
► O presente trabalho apresenta a síntese e a caracterização de um derivado de quitosana anfifílica preparado a partir da reação de despolimerização parcial da quitosana…
(more)
▼ O presente trabalho apresenta a síntese e a caracterização de um derivado de quitosana anfifílica preparado a partir da reação de despolimerização parcial da quitosana comercial, bem como a influência de ambos os polímeros (quitosana anfifílica e quitosana comercial) sobre as propriedades espectroscópicas da curcumina (CUR). Na etapa inicial, a quitosana comercial foi caracterizada e despolimerizada. Em seguida, foram realizadas reações de substituições para a inserção de grupos hidrofílicos (cloreto de 2-cloro-N,N-dietiletilamina - DEAE) e grupos hidrofóbicos (dodecil - DD) no polímero. O grau médio de substituição por grupos DEAE e DD foram determinados por Espectroscopia de Ressonância Magnética Nuclear de Hidrogênio (RMN de 1H). A Concentração de Agregação Crítica (CAC) da quitosana anfifílica foi determinada (0,011 g L-1) utilizando pireno como sonda fluorescente. As propriedades fotofísicas da CUR na presença das quitosanas comercial e
anfifílica foram estudadas por meio de técnicas de Espectroscopia de UV-Visível e de Fluorescência. Os espectros de absorção da desse corante na presença da quitosana modificada, em concentrações acima da CAC, apresentaram deslocamento para o azul, formação da banda em 360 nm e redução da absorbância em 420-425 nm, indicando que a quitosana modificada estabilizou as moléculas da CUR na forma ceto. Nos espectros de fluorescência também foi observado deslocamento para o azul, em contrapartida, a intensidade de emissão aumentou com o aumento da concentração do polímero modificado. Resultados similares foram obtidos para CUR em diferentes solventes, onde foi observado maior intensidade de emissão e deslocamento da banda para menores comprimentos de onda com a diminuição da polaridade do solvente. O equilíbrio tautomérico da CUR é deslocado para a forma ceto em solventes apolares. O valor de rendimento quântico obtido foi maior para o cromóforo em quitosana modificada (QM= 0,05 g/L, acima
da CAC) do que nos outros ambientes poliméricos estudados. A porcentagem de degradação da CUR em QM 0,05 g L-1 foi menor em comparação a degradação nos outros meios. Essa concentração de QM está associada à sua forma agregada, onde estão presentes ambientes hidrofóbicos. A presença dos grupamentos DD na QM promove a formação de ambientes apolares que podem envolver as moléculas do corante, proporcionando maior estabilidade.
This work presents the synthesis and characterization of an amphiphilic chitosan derivative prepared from deacetylation of commercial chitosan, as well as both polymers influence (amphiphilic and commercial chitosan) regarding the spectroscopic properties of curcumin. Firstly, the commercial chitosan was characterized and depolymerized. Then, the substitution reactions were carried out to insert hydrophilic groups (DEAE) and hydrophobic groups (dodecyl), being the average degree of substitution by DEAE and dodecyl groups determined by Hydrogen Nuclear
Magnetic Resonance Spectroscopy (1H NMR). The Critical Aggregation Concentration (CAC) of amphiphilic chitosan…
Advisors/Committee Members: Carla Cristina Schmitt Cavalheiro, Miguel Guillermo Neumann, Kleber Thiago de Oliveira.
Subjects/Keywords: curcumina; fotofísica; quitosana; chitosan; curcumina; photophysics
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Fanchiotti, B. G. (2019). Estudo da estabilidade da curcumina em quitosanas comercial e anfifílica. (Masters Thesis). University of São Paulo. Retrieved from http://www.teses.usp.br/teses/disponiveis/75/75134/tde-05062019-134029/
Chicago Manual of Style (16th Edition):
Fanchiotti, Brenda Gomes. “Estudo da estabilidade da curcumina em quitosanas comercial e anfifílica.” 2019. Masters Thesis, University of São Paulo. Accessed April 23, 2021.
http://www.teses.usp.br/teses/disponiveis/75/75134/tde-05062019-134029/.
MLA Handbook (7th Edition):
Fanchiotti, Brenda Gomes. “Estudo da estabilidade da curcumina em quitosanas comercial e anfifílica.” 2019. Web. 23 Apr 2021.
Vancouver:
Fanchiotti BG. Estudo da estabilidade da curcumina em quitosanas comercial e anfifílica. [Internet] [Masters thesis]. University of São Paulo; 2019. [cited 2021 Apr 23].
Available from: http://www.teses.usp.br/teses/disponiveis/75/75134/tde-05062019-134029/.
Council of Science Editors:
Fanchiotti BG. Estudo da estabilidade da curcumina em quitosanas comercial e anfifílica. [Masters Thesis]. University of São Paulo; 2019. Available from: http://www.teses.usp.br/teses/disponiveis/75/75134/tde-05062019-134029/
Wesleyan University
15.
Moreno, Andrew Thomas.
The Photophysical Characterization of the Guanine Analogue 6-methylisoxanthopterin in DNA Oligomers and Its Application to Probing DNA-Protein Interactions:.
Degree: Wesleyan University
URL: https://doi.org/10.14418/wes01.3.34
;
https://digitalcollections.wesleyan.edu/object/ir-2247
Subjects/Keywords: photophysics; DNA; protein;
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Moreno, A. T. (n.d.). The Photophysical Characterization of the Guanine Analogue 6-methylisoxanthopterin in DNA Oligomers and Its Application to Probing DNA-Protein Interactions:. (Masters Thesis). Wesleyan University. Retrieved from https://doi.org/10.14418/wes01.3.34 ; https://digitalcollections.wesleyan.edu/object/ir-2247
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Chicago Manual of Style (16th Edition):
Moreno, Andrew Thomas. “The Photophysical Characterization of the Guanine Analogue 6-methylisoxanthopterin in DNA Oligomers and Its Application to Probing DNA-Protein Interactions:.” Masters Thesis, Wesleyan University. Accessed April 23, 2021.
https://doi.org/10.14418/wes01.3.34 ; https://digitalcollections.wesleyan.edu/object/ir-2247.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
MLA Handbook (7th Edition):
Moreno, Andrew Thomas. “The Photophysical Characterization of the Guanine Analogue 6-methylisoxanthopterin in DNA Oligomers and Its Application to Probing DNA-Protein Interactions:.” Web. 23 Apr 2021.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Vancouver:
Moreno AT. The Photophysical Characterization of the Guanine Analogue 6-methylisoxanthopterin in DNA Oligomers and Its Application to Probing DNA-Protein Interactions:. [Internet] [Masters thesis]. Wesleyan University; [cited 2021 Apr 23].
Available from: https://doi.org/10.14418/wes01.3.34 ; https://digitalcollections.wesleyan.edu/object/ir-2247.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Council of Science Editors:
Moreno AT. The Photophysical Characterization of the Guanine Analogue 6-methylisoxanthopterin in DNA Oligomers and Its Application to Probing DNA-Protein Interactions:. [Masters Thesis]. Wesleyan University; Available from: https://doi.org/10.14418/wes01.3.34 ; https://digitalcollections.wesleyan.edu/object/ir-2247
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Virginia Tech
16.
Rowe, Jennifer Maria.
Luminescent Properties of Anthracene-based Metal-Organic Frameworks.
Degree: MS, Chemistry, 2016, Virginia Tech
URL: http://hdl.handle.net/10919/71684
► Metal-organic frameworks (MOFs) are crystalline materials composed of metal clusters and organic ligands. MOFs that exhibit photoluminescence are promising materials for a broad range of…
(more)
▼ Metal-organic frameworks (MOFs) are crystalline materials composed of metal clusters and organic ligands. MOFs that exhibit photoluminescence are promising materials for a broad range of applications. Due to their structural tunability and crystalline nature, luminescent MOFs also provide an excellent platform for studying structure–property relationships of materials.
The photophysical properties of three anthracene-dicarboxylic acids – 1,4-anthracene dicarboxylic acid (1,4-ADCA), 2,6-anthracene dicarboxylic acid (2,6-ADCA) and 9,10-anthracene dicarboxylic acid (9,10-ADCA) – were studied in a series of polar aprotic solvents using steady-state absorption, steady-state emission spectroscopy and time-correlated single photon counting (TCSPC) emission lifetime spectroscopy. The addition of carboxylic acid functional groups on the anthracene ring alters photophysical properties to varying degrees depending on the location and protonation state. Density functional theory (DFT) calculations reveal that the lowest-energy ground-state structures of both 2,6-ADCA and 1,4-ADCA have dihedral angles between the carboxylic acids and aromatic planes of θ = 0°, while the same dihedral angle increases to θ = 56.6° for 9,10-ADCA. Time-dependent DFT calculations suggest that the carboxyl groups of 1,4-ADCA and 2,6-ADCA remain coplanar with the anthracene ring system in the excited state. In contrast, the calculations reveal significant changes between the ground and excited geometries for 9,10-ADCA and puckering of the anthracene moiety of is observed.
The three anthracene dicarboxylic acids were then incorporated into zirconium-based MOFs. The MOF structures were characterized using powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). The steady-state absorption and emission spectra as well as the fluorescence lifetimes of the MOFs were compared to that of the corresponding ligand in solution. The MOFs comprising 9,10-ADCA and 2,6-ADCA formed highly crystalline octahedral shaped crystals and were found to be isostructural with the well-known UiO-66 and UiO-67 frameworks. However, incorporation of the 1,4-ADCA ligand resulted in large rod-shaped crystals. The absorption spectra of the MOFs are broadened and redshifted compared with that of the corresponding free ligands. The emission spectra of the MOFs constructed from 9,10-ADCA and 1,4-ADCA display emission bands that resemble that of the free ligand in acidic solutions, but are slightly broadened and redshifted in the MOF. Little difference is observed between that of 2,6-ADCA within the MOF and in acidic solution. The broadening and redshift observed in the absorption and emission is indicative of intermolecular interactions between anthracene units and/or with the Zr4+ clusters. The fluorescence lifetimes measured for the anthracene-based MOFs show a long component, comparable to the lifetime of the free ligand, along with shorter component. This may also suggest intermolecular interactions between chromophores in the MOFs.
Altogether, derivatization of…
Advisors/Committee Members: Morris, Amanda J. (committeechair), Morris, John R. (committee member), Tissue, Brian M. (committee member).
Subjects/Keywords: Metal-Organic Frameworks; luminescence; photophysics; anthracene
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Rowe, J. M. (2016). Luminescent Properties of Anthracene-based Metal-Organic Frameworks. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/71684
Chicago Manual of Style (16th Edition):
Rowe, Jennifer Maria. “Luminescent Properties of Anthracene-based Metal-Organic Frameworks.” 2016. Masters Thesis, Virginia Tech. Accessed April 23, 2021.
http://hdl.handle.net/10919/71684.
MLA Handbook (7th Edition):
Rowe, Jennifer Maria. “Luminescent Properties of Anthracene-based Metal-Organic Frameworks.” 2016. Web. 23 Apr 2021.
Vancouver:
Rowe JM. Luminescent Properties of Anthracene-based Metal-Organic Frameworks. [Internet] [Masters thesis]. Virginia Tech; 2016. [cited 2021 Apr 23].
Available from: http://hdl.handle.net/10919/71684.
Council of Science Editors:
Rowe JM. Luminescent Properties of Anthracene-based Metal-Organic Frameworks. [Masters Thesis]. Virginia Tech; 2016. Available from: http://hdl.handle.net/10919/71684
University of Rochester
17.
Larkin, John Michael (1970 - ).
Optical and photodynamic properties of higher-lying
states of rose bengal.
Degree: PhD, 2007, University of Rochester
URL: http://hdl.handle.net/1802/4370
► We have studied the photophysics and photochemistry of the higher-lying triplet states of rose bengal (tetraiodo-tetrachlorofluorescein) in water. Triplet-triplet absorption spectroscopy is used to identify…
(more)
▼ We have studied the photophysics and photochemistry
of the higher-lying triplet states of rose bengal
(tetraiodo-tetrachlorofluorescein) in water.
Triplet-triplet absorption spectroscopy is used to identify a
previously undescribed triplet state of rose bengal with an
absorption cross section of (1.1 ± 0.1) ×
10−16 cm2 at 1064 nm.
This state is the least energetic triplet state, excluding
T1, to be identified, so it will be denoted
as T2. Two-step
excitation techniques for measuring reverse intersystem crossing,
an intersystem crossing from a higher-lying triplet state to a
singlet state, are described. The method of two-step laser-induced
fluorescence is used to determine the quantum yield of reverse
intersystem crossing for three higher-lying triplet states of rose
bengal. Reverse intersystem crossing yields of 0.0076 ± 0.0002,
<0.06, and 0.12 ± 0.02 are found for the triplet states excited
by 1064-, 632-, 532-nm light, denoted respectively as
T2, T3 and
T4. Bond cleavage may also follow excitation
of a higher-lying state. Other workers have found evidence for this
photochemical process from T3 but not
T4. The method of two-step laser-induced
bleaching was used to determine whether bond cleavage occurs from
T2. No evidence was found for a such a
process. It had been hypothesized that reverse intersystem crossing
was responsible for the lack of bond cleavage from
T4. A theoretical investigation based on
kinetic models including reverse intersystem crossing shows that
variations in the yield of this process would produce only small
changes in the yield of photoproducts formed by bond
cleavage. A two-photon absorption cross section
of 0.028 ± 0.001 GM for rose bengal excited by 1064-nm light is
determined using a fluorescence technique. The impact of
higher-lying states on multiphoton excitation is discussed, and it
is shown that the neglect of reverse intersystem crossing can lead
to an apparent enhancement of the two-photon absorption cross
section in the analysis of fluorescence data.
Subjects/Keywords: Tetraiodo-tetrachlorofluorescein; Photophysics; Photochemistry
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Larkin, J. M. (. -. ). (2007). Optical and photodynamic properties of higher-lying
states of rose bengal. (Doctoral Dissertation). University of Rochester. Retrieved from http://hdl.handle.net/1802/4370
Chicago Manual of Style (16th Edition):
Larkin, John Michael (1970 - ). “Optical and photodynamic properties of higher-lying
states of rose bengal.” 2007. Doctoral Dissertation, University of Rochester. Accessed April 23, 2021.
http://hdl.handle.net/1802/4370.
MLA Handbook (7th Edition):
Larkin, John Michael (1970 - ). “Optical and photodynamic properties of higher-lying
states of rose bengal.” 2007. Web. 23 Apr 2021.
Vancouver:
Larkin JM(-). Optical and photodynamic properties of higher-lying
states of rose bengal. [Internet] [Doctoral dissertation]. University of Rochester; 2007. [cited 2021 Apr 23].
Available from: http://hdl.handle.net/1802/4370.
Council of Science Editors:
Larkin JM(-). Optical and photodynamic properties of higher-lying
states of rose bengal. [Doctoral Dissertation]. University of Rochester; 2007. Available from: http://hdl.handle.net/1802/4370
Temple University
18.
Pochas, Christopher Michael.
The Effects of Vibronic Coupling on the Photophysics of Excitons and Polarons in Ordered and Disordered π-Conjugated Molecular Aggregates.
Degree: PhD, 2014, Temple University
URL: http://digital.library.temple.edu/u?/p245801coll10,323662
► Chemistry
A theoretical model describing photophysics of π-conjugated aggregates, such as molecular crystals and polymer thin films, is developed. A Holstein-like Hamiltonian expressed with a…
(more)
▼ Chemistry
A theoretical model describing photophysics of π-conjugated aggregates, such as molecular crystals and polymer thin films, is developed. A Holstein-like Hamiltonian expressed with a multi-particle basis set is used to evaluate absorption and photoluminescence (PL) spectra of neutral excitons as well as charge modulation spectra (CMS) and transient absorption spectra (TAS) of positively charges hole-type polarons. The results are used to develop a better theoretical understanding of the organic electronics being studied and their photophysics, and also to probe the morphology of poly(3-hexylthiophene) (P3HT) thin films, which are used in photovoltaic devices.
Temple University – Theses
Advisors/Committee Members: Spano, Francis C.;, Matsika, Spiridoula, Voelz, Vincent, Burkhardt, T. W. (Theodore W.);.
Subjects/Keywords: Physical chemistry;
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Pochas, C. M. (2014). The Effects of Vibronic Coupling on the Photophysics of Excitons and Polarons in Ordered and Disordered π-Conjugated Molecular Aggregates. (Doctoral Dissertation). Temple University. Retrieved from http://digital.library.temple.edu/u?/p245801coll10,323662
Chicago Manual of Style (16th Edition):
Pochas, Christopher Michael. “The Effects of Vibronic Coupling on the Photophysics of Excitons and Polarons in Ordered and Disordered π-Conjugated Molecular Aggregates.” 2014. Doctoral Dissertation, Temple University. Accessed April 23, 2021.
http://digital.library.temple.edu/u?/p245801coll10,323662.
MLA Handbook (7th Edition):
Pochas, Christopher Michael. “The Effects of Vibronic Coupling on the Photophysics of Excitons and Polarons in Ordered and Disordered π-Conjugated Molecular Aggregates.” 2014. Web. 23 Apr 2021.
Vancouver:
Pochas CM. The Effects of Vibronic Coupling on the Photophysics of Excitons and Polarons in Ordered and Disordered π-Conjugated Molecular Aggregates. [Internet] [Doctoral dissertation]. Temple University; 2014. [cited 2021 Apr 23].
Available from: http://digital.library.temple.edu/u?/p245801coll10,323662.
Council of Science Editors:
Pochas CM. The Effects of Vibronic Coupling on the Photophysics of Excitons and Polarons in Ordered and Disordered π-Conjugated Molecular Aggregates. [Doctoral Dissertation]. Temple University; 2014. Available from: http://digital.library.temple.edu/u?/p245801coll10,323662
Vanderbilt University
19.
Reid, Kemar Ricardo.
Unraveling the Interplay between Structure and Photophysics in Colloidal Quantum Dot Nanostructures.
Degree: PhD, Interdisciplinary Materials Science, 2019, Vanderbilt University
URL: http://hdl.handle.net/1803/10698
► Colloidal quantum dots (QDs) make up a class of nanomaterials that provide a remarkable platform for engineering photophysical properties tailored to a range of applications…
(more)
▼ Colloidal quantum dots (QDs) make up a class of nanomaterials that provide a remarkable platform for engineering photophysical properties tailored to a range of applications of considerable technological value, including energy-efficient LEDs, robust biological probes, low-threshold solution-processed lasers, advanced photocatalysts and single-photon sources for quantum technologies. Underpinning these uses of QDs lay more fundamental investigations into the role of structure on absorption, energy relaxation, charge separation and charge recombination in order to achieve complete control over their photophysical behavior. However, with complex interfaces and diverging morphologies in synthetic products, QDs are remarkably complex nanostructured materials. It is therefore challenging to develop detailed structure-function relationships at the ensemble scale—where the properties of an array of structures are simultaneously determined. To decode this information, it is necessary to study QD nanostructures one at a time. In this work, single QD investigations were applied to three different QD systems to better understand the interplay between structure and
photophysics in these materials. From revealing the role of strain-induced structural changes on the color purity of CdSe-CdS core-shell QDs, to a thick-shell in suppressing random intermittent emission in cadmium-free InP QD nanostructures, these investigations continually point to the negative impact of structural heterogeneity on the properties of the ensemble. The implementation of a correlative technique to measure the structure and
photophysics of the same QD facilitated a detailed examination of this heterogeneity in semiconductor nanorods—revealing the detrimental effects of surface roughness on the quantum efficiency of the material. The advanced characterization of QDs afforded by this technique also has far-reaching implications for QD development and could be used to inform methods to orchestrate the assembly of QD nanostructures with precisely tuned photophysical properties.
Advisors/Committee Members: Jason G. Valentine (committee member), Janet E. Macdonald (committee member), Richard F. Haglund (committee member), Rizia Bardhan (committee member), Sandra J. Rosenthal (Committee Chair).
Subjects/Keywords: photophysics; atomic structure; electron microscopy; optical spectroscopy; correlation; quantum dot
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Reid, K. R. (2019). Unraveling the Interplay between Structure and Photophysics in Colloidal Quantum Dot Nanostructures. (Doctoral Dissertation). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/10698
Chicago Manual of Style (16th Edition):
Reid, Kemar Ricardo. “Unraveling the Interplay between Structure and Photophysics in Colloidal Quantum Dot Nanostructures.” 2019. Doctoral Dissertation, Vanderbilt University. Accessed April 23, 2021.
http://hdl.handle.net/1803/10698.
MLA Handbook (7th Edition):
Reid, Kemar Ricardo. “Unraveling the Interplay between Structure and Photophysics in Colloidal Quantum Dot Nanostructures.” 2019. Web. 23 Apr 2021.
Vancouver:
Reid KR. Unraveling the Interplay between Structure and Photophysics in Colloidal Quantum Dot Nanostructures. [Internet] [Doctoral dissertation]. Vanderbilt University; 2019. [cited 2021 Apr 23].
Available from: http://hdl.handle.net/1803/10698.
Council of Science Editors:
Reid KR. Unraveling the Interplay between Structure and Photophysics in Colloidal Quantum Dot Nanostructures. [Doctoral Dissertation]. Vanderbilt University; 2019. Available from: http://hdl.handle.net/1803/10698
Penn State University
20.
Doucette, Grayson S.
COARSE TO FINE: TUNING MOLECULAR PACKING TO PINPOINT TRIPLET PAIR SEPARATION MECHANISMS AND THE ROLE OF MOLECULAR COUPLING.
Degree: 2019, Penn State University
URL: https://submit-etda.libraries.psu.edu/catalog/17022gsd135
► Research and development of renewable energy systems is a national priority. Existing technologies cannot fulfill the energy needs of an ever-progressing world. Focusing on solar…
(more)
▼ Research and development of renewable energy systems is a national priority. Existing technologies cannot fulfill the energy needs of an ever-progressing world. Focusing on solar energy, singlet fission (SF) is a potential avenue to improve the performance of existing solar technology. By creating two useable charges from a single photon, tandem and photon multiplier photovoltaics can make more efficient use of the solar spectrum. Currently, only a small number of molecules and polymers have been found to meet the energetic requirements for singlet fission, and among those, a broad range of SF rates and yields exists. While many factors influence intermolecular singlet fission, the role of molecular coupling in driving both the photogeneration of two triplet excitations and subsequent transport are of paramount importance. Many theoretical accounts and some experimental work make clear the need to tune coupling to be strong enough such that SF occurs rapidly and efficiently while not too strong as to prevent binding and annihilation of triplet pairs. Unfortunately, a hurdle in SF research is the means of isolating the effect of coupling without drastically altering the electronic structure of molecules and doing so in device relevant films. This study takes two steps toward continuous control of coupling to uncover mechanistic features of SF as well as to glimpse at the turning point in coupling strength.
The first step employs polymorphs of the molecule 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pn) to form two distinct molecular packing motifs in thin film samples. These motifs alter intermolecular interactions without changing the energetics of isolated molecules. Transient absorption was used to observe the effect on the separation of correlated triplet pairs (CTP) formed from singlet fission. Mechanistic parallels were drawn by correlating the initial CTP separation rates on the femtosecond timescale with triplet transfer controlled diffusion and annihilation rates on the nanosecond timescale. Similar polymorph dependence suggested CTP separation occurs via triplet transfer as well. As a result, controlling the efficiency of SF yield requires control of both singlet and triplet mixing necessary for CTP formation and triplet orbital coupling for separation. The next experimental step honed in on tuning both singlet and triplet coupling with the use of pressure to test for a coupling strength tipping point. By focusing on a single polymorph of TIPS-Pn, pressure enabled gradual changes in intermolecular distance and slip which can have large impacts on coupling without any change to monomer energetics. Following similar experimental procedure to the polymorph work, dynamics of CTPs and separated triplets showed the onset of geminate recombination at higher pressure. Effectively, higher pressure resulted in either stronger coupling between CTPs and the ground state or produced significant triplet pair binding energy to prevent their separation. While future work is targeted at various pentacene derivatives…
Advisors/Committee Members: John B Asbury, Dissertation Advisor/Co-Advisor, John B Asbury, Committee Chair/Co-Chair, Suzanne E Mohney, Committee Member, Joshua Alexander Robinson, Committee Member, Noel Christopher Giebink, Outside Member.
Subjects/Keywords: Singlet Fission; High Pressure; Intermolecular Coupling; Photophysics; Pentacene; Polymorph
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Doucette, G. S. (2019). COARSE TO FINE: TUNING MOLECULAR PACKING TO PINPOINT TRIPLET PAIR SEPARATION MECHANISMS AND THE ROLE OF MOLECULAR COUPLING. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/17022gsd135
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Doucette, Grayson S. “COARSE TO FINE: TUNING MOLECULAR PACKING TO PINPOINT TRIPLET PAIR SEPARATION MECHANISMS AND THE ROLE OF MOLECULAR COUPLING.” 2019. Thesis, Penn State University. Accessed April 23, 2021.
https://submit-etda.libraries.psu.edu/catalog/17022gsd135.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Doucette, Grayson S. “COARSE TO FINE: TUNING MOLECULAR PACKING TO PINPOINT TRIPLET PAIR SEPARATION MECHANISMS AND THE ROLE OF MOLECULAR COUPLING.” 2019. Web. 23 Apr 2021.
Vancouver:
Doucette GS. COARSE TO FINE: TUNING MOLECULAR PACKING TO PINPOINT TRIPLET PAIR SEPARATION MECHANISMS AND THE ROLE OF MOLECULAR COUPLING. [Internet] [Thesis]. Penn State University; 2019. [cited 2021 Apr 23].
Available from: https://submit-etda.libraries.psu.edu/catalog/17022gsd135.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Doucette GS. COARSE TO FINE: TUNING MOLECULAR PACKING TO PINPOINT TRIPLET PAIR SEPARATION MECHANISMS AND THE ROLE OF MOLECULAR COUPLING. [Thesis]. Penn State University; 2019. Available from: https://submit-etda.libraries.psu.edu/catalog/17022gsd135
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of California – Merced
21.
Zeng, Youhong.
Photophysics and Photochemistry of Ⅱ-Ⅵ Semiconductor Nanocrystals.
Degree: Chemistry and Chemical Biology, 2017, University of California – Merced
URL: http://www.escholarship.org/uc/item/7mx9g318
► Colloidally synthesized, 0D semiconductor nanocrystals, also referred to as Quantum Dots (QDs), are promising light-harvesting materials which have found increasing use in photovoltaic devices, LEDs…
(more)
▼ Colloidally synthesized, 0D semiconductor nanocrystals, also referred to as Quantum Dots (QDs), are promising light-harvesting materials which have found increasing use in photovoltaic devices, LEDs and other optoelectronic devices. In the past two decades, they have been extensively studied in terms of their photophysical and photochemical properties. One of the most prominent features of this class of material is their size tunable optical properties, which can be explained by the quantum size effect, whereby the bandgap of a semiconductor is pushed to a larger value as the exciton experiences increased confinement. In the strong confinement regime, the degeneracy of the hole states gives rise to the fine structure of the band-edge exciton, which helps explain their unusually long radiative lifetimes (~1μs at 10 K) relative to the bulk exciton recombination time (1ns), detailed in Chapter 1. In Chapter 2, the size dependence of the radiative lifetimes of CdSe quantum dots is illustrated and compared to the calculated results using the Einstein coefficients. The quantum yield of CdSe particles is strongly related to the ratio of radiative and nonradiative recombination processes. This affects the size dependence of radiative lifetimes, and is the reason for a large discrepancy in the literature. In this section, we compare the results obtained for particles synthesized using a standard method and those obtained from an optimized synthesis. To correctly calculate the radiative lifetime of CdSe particles, it is found that three factors need to be considered: size-dependent integrated extinction coefficient, the bandedge frequency and the Boltzmann fraction of population of dark versus bright states within the lowest energy exciton fine structure. In Chapter 3, the mechanism of two-photon darkening is elucidated. When the CdSe particles are subjected to high power density irradiation, they demonstrate a prompt photoluminescence depletion, followed by a recovery in polar solvents, on the time scale of tens of minutes. The mechanism proposed is that a significant fraction of biexcitons is generated under intense irradiation, which can then undergo fast Auger recombination by transferring the recombination energy of the exciton to the remaining hole and excite it higher into the valence band. The excited hole can either relax back to the top of the valence band or tunnel out to the surface and ionize a ligand, specifically, trioctylphosphine. In the latter case, the ionization forms QD-/TOP+, which has a certain probability to dissociate into QD- and TOP+. The resulting QD- is dark, because it is negatively charged and unligated, which is attributed to the prompt photoluminescence (PL) depletion. The depletion of PL is reversible, when certain passivating ligands are present in solution, and indeed it is the charge neutralization and ligand reattachment/reorganization that determines the time scale of the PL recovery. The details are given in Chapter 3. In Chapter 4, we provide an examination of the excited hole…
Subjects/Keywords: Physical chemistry; Nanoscience; Chemistry; nanocrystals; photochemistry; photophysics; quantum dots; semiconductor
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Zeng, Y. (2017). Photophysics and Photochemistry of Ⅱ-Ⅵ Semiconductor Nanocrystals. (Thesis). University of California – Merced. Retrieved from http://www.escholarship.org/uc/item/7mx9g318
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Zeng, Youhong. “Photophysics and Photochemistry of Ⅱ-Ⅵ Semiconductor Nanocrystals.” 2017. Thesis, University of California – Merced. Accessed April 23, 2021.
http://www.escholarship.org/uc/item/7mx9g318.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Zeng, Youhong. “Photophysics and Photochemistry of Ⅱ-Ⅵ Semiconductor Nanocrystals.” 2017. Web. 23 Apr 2021.
Vancouver:
Zeng Y. Photophysics and Photochemistry of Ⅱ-Ⅵ Semiconductor Nanocrystals. [Internet] [Thesis]. University of California – Merced; 2017. [cited 2021 Apr 23].
Available from: http://www.escholarship.org/uc/item/7mx9g318.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Zeng Y. Photophysics and Photochemistry of Ⅱ-Ⅵ Semiconductor Nanocrystals. [Thesis]. University of California – Merced; 2017. Available from: http://www.escholarship.org/uc/item/7mx9g318
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
22.
Petrović Jovana.
The analysis of the charge carrier photogeneration and recombination in conductive polymers: Photodetector applications.
Degree: PhD, Electrical Engineering, 2012, University of Belgrade
URL: http://dx.doi.org/10.2298/BG20120620PETROVIC
;
http://eteze.bg.ac.rs/application/showtheses?thesesId=226
;
https://fedorabg.bg.ac.rs/fedora/get/o:5486/bdef:Content/get
;
http://vbs.rs/scripts/cobiss?command=SEARCH&base=99999&select=ID=43463439
► Due to their numerous advantages over the classical semiconductors conductive polymers are among the most promising materials for modern optoelectronic applications. In order to fully…
(more)
▼ Due to their numerous advantages over the classical semiconductors conductive
polymers are among the most promising materials for modern optoelectronic
applications. In order to fully exploit their potential it is of the greatest
interest to elucidate the diverse and complex physical processes which occur
in these materials. In this thesis the charge carrier photogeneration
mechanisms in conductive polymers are systematized starting from the
extensive and detailed literature review. The photocarrier transport and
recombination are also considered. The polymer photodetector model is
developed consisting of the continuity and diffusion equation for singlet
excitons and the continuity and drift-diffusion equation for hole polarons.
The model is applied to the ITO/PEDOT:PSS/MEH-PPV/A1 detectors. The
photocurrent spectra for the devices with three different thin film
thicknesses (35 nm, 100 nm i 215 nm) in the wide range of incident light
intensities (10-4 mW/cm2 - 10-2 mW/cm2) and bias voltages (-8 V to +1 V) are
measured and compared with the model predictions. Based on the comprehensive
photocurrent spectra analysis the thickness dependence of the MEH-PPV
absorption coefficient is discovered. The revealed dependence is
experimentally confirmed. It is also shown that polaron photogeneration
quantum efficiency for this polymer changes with the film thickness. The
ITO/PEDOT:PSS/MEH-PPV/Al photocurrent spectra are reproduced very well by the
model for all devices and operating conditions used in the experiment.
Zahvaljujući brojnim prednostima u odnosu na klasične poluprovodnike provodni
polimeri spadaju u grupu najperspektivnijih optoelektronskih materijala. Da
bi sav njihov potencijal bio iskorišćen neophodno je rasvetliti složene
fizičke procese koji se u ovim materijalima odvijaju. U okviru ove doktorske
disertacije izvršena je sistematizacija mehanizama fotogeneracije nosilaca
naelektrisanja u provodnim polimerima polazeći od opsežnog i detaljnog
pregleda literature. Transport i rekombinacija fotonosilaca su, takođe,
razmatrani. Razvijen je eksitonsko-polaronski model polimerskog
fotodetektora zasnovan na jednačini kontinuiteta i difuzionoj jednačini za
singletne eksitone i jednačini kontinuiteta i drift-difuzionoj jednačini za
šupljinske polarone. Model je primenjen na ITO/REDOT:R55/MENRRV/A1 naprave.
Simulirani spektri fotostruje upoređeni su sa izmerenim za detektore sa tri
različite debljine MEN-RRV filma (35 nm, 100 nm i 215 nm) u širokom opsegu
intenziteta upadne svetlosti (10-4 mW/cm2 - 10-2 mW/cm2) i napona
polarizacije (-8 V do +1 V). Na osnovu sveobuhvatne analize spektra
fotostruje otkrivena je zavisnost koeficijenta apsorpcije MEN-RRV-a od
debljine tankog filma. Dobijena zavisnost je i eksperimentalno potvrđena.
Takođe, pokazano je da se i kvantna efikasnost fotogeneracije polarona menja
sa promenom debljine polimerskog filma. Model dobro reprodukuje spektar
fotostruje za sve naprave i uslove rada obuhvaćene eksperimentom.
Subjects/Keywords: conductive polymers; photophysics; modeling; photodetector; provodni polimeri; fotofizika; modelovanje; fotodetektor
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Jovana, P. (2012). The analysis of the charge carrier photogeneration and recombination in conductive polymers: Photodetector applications. (Doctoral Dissertation). University of Belgrade. Retrieved from http://dx.doi.org/10.2298/BG20120620PETROVIC ; http://eteze.bg.ac.rs/application/showtheses?thesesId=226 ; https://fedorabg.bg.ac.rs/fedora/get/o:5486/bdef:Content/get ; http://vbs.rs/scripts/cobiss?command=SEARCH&base=99999&select=ID=43463439
Chicago Manual of Style (16th Edition):
Jovana, Petrović. “The analysis of the charge carrier photogeneration and recombination in conductive polymers: Photodetector applications.” 2012. Doctoral Dissertation, University of Belgrade. Accessed April 23, 2021.
http://dx.doi.org/10.2298/BG20120620PETROVIC ; http://eteze.bg.ac.rs/application/showtheses?thesesId=226 ; https://fedorabg.bg.ac.rs/fedora/get/o:5486/bdef:Content/get ; http://vbs.rs/scripts/cobiss?command=SEARCH&base=99999&select=ID=43463439.
MLA Handbook (7th Edition):
Jovana, Petrović. “The analysis of the charge carrier photogeneration and recombination in conductive polymers: Photodetector applications.” 2012. Web. 23 Apr 2021.
Vancouver:
Jovana P. The analysis of the charge carrier photogeneration and recombination in conductive polymers: Photodetector applications. [Internet] [Doctoral dissertation]. University of Belgrade; 2012. [cited 2021 Apr 23].
Available from: http://dx.doi.org/10.2298/BG20120620PETROVIC ; http://eteze.bg.ac.rs/application/showtheses?thesesId=226 ; https://fedorabg.bg.ac.rs/fedora/get/o:5486/bdef:Content/get ; http://vbs.rs/scripts/cobiss?command=SEARCH&base=99999&select=ID=43463439.
Council of Science Editors:
Jovana P. The analysis of the charge carrier photogeneration and recombination in conductive polymers: Photodetector applications. [Doctoral Dissertation]. University of Belgrade; 2012. Available from: http://dx.doi.org/10.2298/BG20120620PETROVIC ; http://eteze.bg.ac.rs/application/showtheses?thesesId=226 ; https://fedorabg.bg.ac.rs/fedora/get/o:5486/bdef:Content/get ; http://vbs.rs/scripts/cobiss?command=SEARCH&base=99999&select=ID=43463439
Vrije Universiteit Amsterdam
23.
Ravensbergen, J.
Photophysics of solar fuel materials
.
Degree: 2015, Vrije Universiteit Amsterdam
URL: http://hdl.handle.net/1871/53504
Subjects/Keywords: photophysics;
solar fuel;
spectroscopy
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Ravensbergen, J. (2015). Photophysics of solar fuel materials
. (Doctoral Dissertation). Vrije Universiteit Amsterdam. Retrieved from http://hdl.handle.net/1871/53504
Chicago Manual of Style (16th Edition):
Ravensbergen, J. “Photophysics of solar fuel materials
.” 2015. Doctoral Dissertation, Vrije Universiteit Amsterdam. Accessed April 23, 2021.
http://hdl.handle.net/1871/53504.
MLA Handbook (7th Edition):
Ravensbergen, J. “Photophysics of solar fuel materials
.” 2015. Web. 23 Apr 2021.
Vancouver:
Ravensbergen J. Photophysics of solar fuel materials
. [Internet] [Doctoral dissertation]. Vrije Universiteit Amsterdam; 2015. [cited 2021 Apr 23].
Available from: http://hdl.handle.net/1871/53504.
Council of Science Editors:
Ravensbergen J. Photophysics of solar fuel materials
. [Doctoral Dissertation]. Vrije Universiteit Amsterdam; 2015. Available from: http://hdl.handle.net/1871/53504
Boston College
24.
Dimitrov, Stoichko Dimitrov.
Ultrafast Excited State Dynamics in DNA and other
Nanomaterials.
Degree: PhD, Chemistry, 2010, Boston College
URL: http://dlib.bc.edu/islandora/object/bc-ir:101338
► Understanding the electronic nature of DNA is profound and has been attempted for decades. Photoexcitation of DNA with UV light deposits electronic energy in the…
(more)
▼ Understanding the electronic nature of DNA is profound
and has been attempted for decades. Photoexcitation of DNA with UV
light deposits electronic energy in the base stack and prepares
highly reactive excited states. These states are precursors for
photoinduced damage reactions which can lead to mutations and
ultimately to cell death. While many DNA photo products have been
isolated and characterized, the primary events immediately after
photon absorption are not yet understood. Recent studies with
ultrafast lasers have revealed that the majority of excess energy
gained by DNA with light absorbance is dissipated on the
femtosecond and picosecond time scales. In this study
double-stranded oligonucleotides with different base sequences,
content and lengths were systematically examined using femtosecond
pump-probe spectroscopy. The results indicate that excitations in
DNA are delocalized over more than two bases and the extent of the
delocalization depends strongly on the structure of the
investigated systems. Exciton delocalization domains in the longer
duplexes are larger than in the shorter ones. Also, single-stranded
oligonucleotides show smaller extent of exciton delocalization than
duplexes with the same length. In addition to the fundamental
studies on DNA
photophysics, the properties and the structure of
new molecular beacons based on thiazole orange dimers were studied.
A full account of the optical and structural properties of the
dimers in different base environments and orientations is presented
here. Currently, the development of efficient ways to utilizing
solar energy is at the forefront of the scientific community due to
the ever rising demand for energy. Both, colloidal semiconductor
nanocrystals and single-walled carbon nanotubes are potential
alternatives to conventional inorganic and organic materials in
photovoltaic devices Thorough understanding of the charge transfer
and related photophysical phenomena in these systems will answer
the question whether these nanomaterials can be applied in future
generations of solar cells. The photoinduced electron transfer in
donor-acceptor CdSe/CdTe heterostructured nanorods, in which CdTe
is grown on top of CdSe in a single rod structure, was studied. The
electron transfer between the two nanocrystals occurs on the
subpicosecond time scale, competing with the ultrafast relaxation
mechanisms in the quantum confined nanocrystals. Furthermore,
investigations on how quantum confinement influences the phonon
wavepackets in semiconductor nanocrystals were carried out. Quantum
beats corresponding to longitudinal optical phonon modes were
observed in the femtosecond pump-probe spectra of colloidal CdTe
nanocrystals. Size-dependent experiments revealed that the optical
phonon frequencies and the exciton-phonon coupling strength do not
depend on the crystal's size. Only the wavepacket dephasing time
was influenced by the diameter of the particles which was
correlated with the hole relaxation to the exciton band edge.
Electron donor-acceptor constructs, based on…
Advisors/Committee Members: Torsten Fiebig (Thesis advisor), Mary Roberts (Thesis advisor).
Subjects/Keywords: DNA; femtosecond spectroscopy; molecular beacons; nanocrystals; nanotubes; photophysics
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Dimitrov, S. D. (2010). Ultrafast Excited State Dynamics in DNA and other
Nanomaterials. (Doctoral Dissertation). Boston College. Retrieved from http://dlib.bc.edu/islandora/object/bc-ir:101338
Chicago Manual of Style (16th Edition):
Dimitrov, Stoichko Dimitrov. “Ultrafast Excited State Dynamics in DNA and other
Nanomaterials.” 2010. Doctoral Dissertation, Boston College. Accessed April 23, 2021.
http://dlib.bc.edu/islandora/object/bc-ir:101338.
MLA Handbook (7th Edition):
Dimitrov, Stoichko Dimitrov. “Ultrafast Excited State Dynamics in DNA and other
Nanomaterials.” 2010. Web. 23 Apr 2021.
Vancouver:
Dimitrov SD. Ultrafast Excited State Dynamics in DNA and other
Nanomaterials. [Internet] [Doctoral dissertation]. Boston College; 2010. [cited 2021 Apr 23].
Available from: http://dlib.bc.edu/islandora/object/bc-ir:101338.
Council of Science Editors:
Dimitrov SD. Ultrafast Excited State Dynamics in DNA and other
Nanomaterials. [Doctoral Dissertation]. Boston College; 2010. Available from: http://dlib.bc.edu/islandora/object/bc-ir:101338
Univerzitet u Beogradu
25.
Petrović, Jovana, 1978-.
Анализа фотогенерације и рекомбинације носилаца
наелектрисања у проводним полимерима са применом на
фотодетекторе.
Degree: Elektrotehnički fakultet, 2013, Univerzitet u Beogradu
URL: https://fedorabg.bg.ac.rs/fedora/get/o:5486/bdef:Content/get
Optoelektronika - Polimerski fotodetektori /
Optoelectronics - Polymer photodetectors
Advisors/Committee Members: Matavulj, Petar, 1971-.Subjects/Keywords: condyctive polymers; photophysics;
photodetector
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Petrović, Jovana, 1. (2013). Анализа фотогенерације и рекомбинације носилаца
наелектрисања у проводним полимерима са применом на
фотодетекторе. (Thesis). Univerzitet u Beogradu. Retrieved from https://fedorabg.bg.ac.rs/fedora/get/o:5486/bdef:Content/get
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Petrović, Jovana, 1978-. “Анализа фотогенерације и рекомбинације носилаца
наелектрисања у проводним полимерима са применом на
фотодетекторе.” 2013. Thesis, Univerzitet u Beogradu. Accessed April 23, 2021.
https://fedorabg.bg.ac.rs/fedora/get/o:5486/bdef:Content/get.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Petrović, Jovana, 1978-. “Анализа фотогенерације и рекомбинације носилаца
наелектрисања у проводним полимерима са применом на
фотодетекторе.” 2013. Web. 23 Apr 2021.
Vancouver:
Petrović, Jovana 1. Анализа фотогенерације и рекомбинације носилаца
наелектрисања у проводним полимерима са применом на
фотодетекторе. [Internet] [Thesis]. Univerzitet u Beogradu; 2013. [cited 2021 Apr 23].
Available from: https://fedorabg.bg.ac.rs/fedora/get/o:5486/bdef:Content/get.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Petrović, Jovana 1. Анализа фотогенерације и рекомбинације носилаца
наелектрисања у проводним полимерима са применом на
фотодетекторе. [Thesis]. Univerzitet u Beogradu; 2013. Available from: https://fedorabg.bg.ac.rs/fedora/get/o:5486/bdef:Content/get
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Colorado
26.
Hughes, Barbara Katherine.
Manipulation of Composition, Morphology, and Surface Chemistry of Semiconductor Quantum Dots for Enhanced Photophysics.
Degree: PhD, Chemistry & Biochemistry, 2013, University of Colorado
URL: https://scholar.colorado.edu/chem_gradetds/88
► Semiconductor quantum dots (QDs) are an interesting class of materials in that they exhibit unique physical properties when compared to their bulk counterparts. These…
(more)
▼ Semiconductor quantum dots (QDs) are an interesting class of materials in that they exhibit unique physical properties when compared to their bulk counterparts. These unique properties and the breadth of tunability which they possess have made QD research a major field of study for more than 20 years for technologies such as catalysis, bio-imaging, solid-state lighting, and solar energy conversion. The primary concern for the application of semiconductor QDs in any field is not only to be able to precisely control physical properties (i.e., optical, electrical, magnetic) but also to understand how to achieve increased stability in these materials. A greater understanding of the chemistry of QD growth, surface construction, and composition are necessary to realize these goals. This thesis explores each of these areas of QD chemistry and the subsequent effects on their photophysical properties. Through manipulation of QD morphology, we have prepared PbSe QD dimers, which has allowed for a better understanding of electronic structure in quantum confined systems. Specifically we have observed a new absorption feature in the 1st exciton QD-dimer spectra, which we assign to a splitting of the 8-fold degenerate 1S level upon fusion of two monomer species. Surface treatment of PbSe QDs with a newly synthesized alkylselenide ligand has led to higher air stability, unique temperature dependent PL properties and the observation of a new surface-related trap level. Alongside producing more stable QDs, the nature of the strong Pb
surface to Se-R bond may also have implications for affecting kinetic processes like carrier relaxation, which could facilitate production of materials that show enhanced multiple exciton generation (MEG) yields. Finally, substitutional doping of PbSe QDs has allowed for modulation of QD compositions and in turn tuning of the dominant carrier type in both solution and in QD films. Although just a small contribution to the larger reservoir of work in this area, these results provide promise for improving stability and efficiency of QD devices for solar energy conversion.
Advisors/Committee Members: Arthur J. Nozik, David M. Jonas, Garry Rumbles, Gordana Dukovic, Ivan Smalyukh.
Subjects/Keywords: morphology; photophysics; quantum dots; surface chemistry; Physical Chemistry
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Hughes, B. K. (2013). Manipulation of Composition, Morphology, and Surface Chemistry of Semiconductor Quantum Dots for Enhanced Photophysics. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/88
Chicago Manual of Style (16th Edition):
Hughes, Barbara Katherine. “Manipulation of Composition, Morphology, and Surface Chemistry of Semiconductor Quantum Dots for Enhanced Photophysics.” 2013. Doctoral Dissertation, University of Colorado. Accessed April 23, 2021.
https://scholar.colorado.edu/chem_gradetds/88.
MLA Handbook (7th Edition):
Hughes, Barbara Katherine. “Manipulation of Composition, Morphology, and Surface Chemistry of Semiconductor Quantum Dots for Enhanced Photophysics.” 2013. Web. 23 Apr 2021.
Vancouver:
Hughes BK. Manipulation of Composition, Morphology, and Surface Chemistry of Semiconductor Quantum Dots for Enhanced Photophysics. [Internet] [Doctoral dissertation]. University of Colorado; 2013. [cited 2021 Apr 23].
Available from: https://scholar.colorado.edu/chem_gradetds/88.
Council of Science Editors:
Hughes BK. Manipulation of Composition, Morphology, and Surface Chemistry of Semiconductor Quantum Dots for Enhanced Photophysics. [Doctoral Dissertation]. University of Colorado; 2013. Available from: https://scholar.colorado.edu/chem_gradetds/88
University of Colorado
27.
Donohoo-Vallett, Paul John.
Control of Photophysical Processes Through Nuclear Motions — Design and Characterization.
Degree: PhD, Chemistry & Biochemistry, 2013, University of Colorado
URL: https://scholar.colorado.edu/chem_gradetds/94
► In order to achieve third-generation solar devices, the basic photophysics of light-absorbing materials must be thoroughly understood. Herein, vibrational motions are explored as potential…
(more)
▼ In order to achieve third-generation solar devices, the basic
photophysics of light-absorbing materials must be thoroughly understood. Herein, vibrational motions are explored as potential methods by which excited-state dynamics can be controlled. In an effort to prevent charge-recombination, vibrationally activated photoinduced dissociative electron transfer (ET) of the type [Ru
II(A)
n(L–X)]
2+ + hν⟶ [Ru
III(A)
n(L–X)•
–]
2+*⟶ [Ru
III (A)
n(L•)]
3+ + X
– (L = polypyridine ligand; X = halogen; A = ancillary ligand) is explored computationally and experimentally. Density functional theory (DFT) calculations employed a thermochemical cycle to determine structural and electronic factors influencing ΔE
rxn. Intramolecular strain is shown to decrease ΔE
rxn and the formation of a contact ion pair (CIP) state is determined to be a favored product. Thus, parent complex [Ru(tpy)
2]
2+ (1) (tpy = 2,2':6',2''-terpyridine) is compared with two compounds [Ru(6,6''-Br
2-tpy)(tpy)]
2+ (2) and [Ru(6,6''-Br
2-tpy)
2]
2+ (3), that incorporate interligand strain. The crystal structure of 3 is distorted due to strain as compared to 1. While electronic absorption in 2 and 3 is weakened relative to transitions in 1, a strong interligand charge transfer (CT) transition is observed. Ultrafast transient absorption spectroscopy revealed coherent vibrational dynamics in 3 and 2 that were assigned to Br motion. In spite of additional strain, the excited-state lifetime of 3 is ~6x longer than 2. Constrained-DFT calculations shows the strain-induced geometric distortions in 3 causes a nesting of excited state surfaces, extending excited-state lifetime. Kinetic evidence is presented for C–Br bond scission in 3 and formation of the predicted CIP.
A secondary project explores singlet fission (SF) — a process where one photon produces two excited-states. DFT calculations are used to explore a series of bistetracene (BT) molecular dimers connected by norbonyl bridges that exhibit through-space and through-bond electronic coupling. Dimer orientation and separation is shown to significantly affect SF driving force, Davydov splitting, and the magnitude of matrix elements important to CT-mediated SF. It is determined that BT1-cis, a norbonyl bridged dimer connected at the 1,2 tetracene positions with both tetracenes extending in the same direction, is most favorable for SF due to an exoergic SF driving force (–119 meV) and increased magnitudes of Davydov splitting and ET matrix elements.
Advisors/Committee Members: Niels H. Damrauer, David M. Jonas, Cortland G. Pierpont, Joel Eaves, Henry Kapteyn.
Subjects/Keywords: density functional theory; electron transfer; photophysics; singlet fission; Chemistry; Physical Chemistry
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Donohoo-Vallett, P. J. (2013). Control of Photophysical Processes Through Nuclear Motions — Design and Characterization. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/94
Chicago Manual of Style (16th Edition):
Donohoo-Vallett, Paul John. “Control of Photophysical Processes Through Nuclear Motions — Design and Characterization.” 2013. Doctoral Dissertation, University of Colorado. Accessed April 23, 2021.
https://scholar.colorado.edu/chem_gradetds/94.
MLA Handbook (7th Edition):
Donohoo-Vallett, Paul John. “Control of Photophysical Processes Through Nuclear Motions — Design and Characterization.” 2013. Web. 23 Apr 2021.
Vancouver:
Donohoo-Vallett PJ. Control of Photophysical Processes Through Nuclear Motions — Design and Characterization. [Internet] [Doctoral dissertation]. University of Colorado; 2013. [cited 2021 Apr 23].
Available from: https://scholar.colorado.edu/chem_gradetds/94.
Council of Science Editors:
Donohoo-Vallett PJ. Control of Photophysical Processes Through Nuclear Motions — Design and Characterization. [Doctoral Dissertation]. University of Colorado; 2013. Available from: https://scholar.colorado.edu/chem_gradetds/94
University of Colorado
28.
Schnitzenbaumer, Kyle J.
The Impact of Chalcogenide Ligands on the Photoexcited States of Cadmium Chalcogenide Quantum Dots.
Degree: PhD, Chemistry & Biochemistry, 2015, University of Colorado
URL: https://scholar.colorado.edu/chem_gradetds/159
► Quantum dots (QDs) are the foundation of many optoelectronic devices because their optical and electronic properties are synthetically tunable. The inherent connection between synthetically…
(more)
▼ Quantum dots (QDs) are the foundation of many optoelectronic devices because their optical and electronic properties are synthetically tunable. The inherent connection between synthetically controllable physical parameters, such as size, shape, and surface chemistry, and QD electronic properties provides flexibility in manipulating excited states. The properties of the ligands that passivate the QD surface and provide such synthetic control, however, are quite different from those that are beneficial for use in optoelectronic devices. In these applications, ligands that promote charge transfer are desired. To this end, significant research efforts have focused on post-synthetic ligand exchange to shorter, more conductive ligand species. Surface ligand identity, however, is a physical parameter intimately tied to QD excited state behavior in addition to charge transfer. A particularly interesting group of ligands, due to the extraordinarily thin ligand shell they create around the QD, are the chalcogenides S
2-, Se
2-, and Te
2-. While promising, little is known about how these chalcogenide ligands affect QD photoexcited states. This dissertation focuses on the impact of chalcogenide ligands on the excited state dynamics of cadmium chalcogenide QDs and associated implications for charge transfer. This is accomplished through a combination of theoretical (Chapters 2, 3, and 6) and experimental (Chapters 2, 4, 5 and 6) methods. We establish a theoretical foundation for describing chalcogenide capped QD photoexcited states and measure the dynamics of these excited states using transient absorption spectroscopy. The presented results highlight the drastic effects surface modification can have on QD photoexcited state dynamics and provide insights for more informed design of optoelectronic systems.
Advisors/Committee Members: Gordana Dukovic, David Jonas, Veronica Bierbaum, Robert Parson, Henry Kapteyn.
Subjects/Keywords: Chalcogenide Ligands; Photophysics; Quantum Dots; Transient Absorption Spectroscopy; Physical Chemistry
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Schnitzenbaumer, K. J. (2015). The Impact of Chalcogenide Ligands on the Photoexcited States of Cadmium Chalcogenide Quantum Dots. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/chem_gradetds/159
Chicago Manual of Style (16th Edition):
Schnitzenbaumer, Kyle J. “The Impact of Chalcogenide Ligands on the Photoexcited States of Cadmium Chalcogenide Quantum Dots.” 2015. Doctoral Dissertation, University of Colorado. Accessed April 23, 2021.
https://scholar.colorado.edu/chem_gradetds/159.
MLA Handbook (7th Edition):
Schnitzenbaumer, Kyle J. “The Impact of Chalcogenide Ligands on the Photoexcited States of Cadmium Chalcogenide Quantum Dots.” 2015. Web. 23 Apr 2021.
Vancouver:
Schnitzenbaumer KJ. The Impact of Chalcogenide Ligands on the Photoexcited States of Cadmium Chalcogenide Quantum Dots. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2021 Apr 23].
Available from: https://scholar.colorado.edu/chem_gradetds/159.
Council of Science Editors:
Schnitzenbaumer KJ. The Impact of Chalcogenide Ligands on the Photoexcited States of Cadmium Chalcogenide Quantum Dots. [Doctoral Dissertation]. University of Colorado; 2015. Available from: https://scholar.colorado.edu/chem_gradetds/159
University of Oxford
29.
Movsisyan, Levon.
Polyyne rotaxanes.
Degree: PhD, 2014, University of Oxford
URL: http://ora.ox.ac.uk/objects/uuid:7f436a99-071f-4cc5-a4b5-5779e1aa3347
;
https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.640047
► This thesis describes the synthesis of polyyne rotaxanes and an investigation of their excited state photophysical properties. The threading of dumbbell-shaped carbon chains with macrocyclic…
(more)
▼ This thesis describes the synthesis of polyyne rotaxanes and an investigation of their excited state photophysical properties. The threading of dumbbell-shaped carbon chains with macrocyclic components is a way to mechanically insulate and control the environment around the carbon chains. The resulting polyyne rotaxanes can serve as model compounds for insulated carbyne. Different strategies have been tested for the synthesis of polyyne rotaxanes with different topologies and structures. Study of rotaxanes in the excited states reveals strong electronic communication between an acetylenic thread and a macrocycle. Chapter 1 summarizes the field of acetylene scaffolding, introducing some recent achievements in acetylene chemistry. General synthetic methods for polyynes are discussed, and an introduction to active metal template synthesis of rotaxanes is given. Chapter 2 describes the synthesis of a family of polyyne rotaxanes with different axle lengths and macrocycles, prepared by homocoupling of terminal alkynes. Synthesis of hexayne rotaxane with functional pyridine end-group is presented and a number of crystal structures of polyyne rotaxanes are analyzed. Chapter 3 demonstrates the use of acetylene cross-coupling in the synthesis of rotaxanes. Synthesis of rotaxanes with different topological structure is provided. Chapter 4 details the excited state properties of polyynes studied by time -resolved spectroscopy. The complexes of rhenium(I) carbonyls with rotaxanes is presented and the excited state energy transfer in rotaxanes is studied. Chapter 5 explores new synthetic strategies for polyyne rotaxanes, using "masked" precursors. It also highlights the potential of carbenoid rearrangement of alkyliden es for the construction of linear and cyclic architectures. Chapter 6 is the summary of the project and general discussion of future directions. There are two appendices in the end of thesis: Appendix A covers the photophysics of rhenium tricarbonyl complex of the hexayne rotaxane with a small macrocycle and Appendix B reports work towards the synthesis of rotaxanes with platinum(II)-alkyne complexes.
Subjects/Keywords: 547; Organic chemistry; Polyynes; rotaxanes; Photophysics; Time-resolved spectroscopy
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Movsisyan, L. (2014). Polyyne rotaxanes. (Doctoral Dissertation). University of Oxford. Retrieved from http://ora.ox.ac.uk/objects/uuid:7f436a99-071f-4cc5-a4b5-5779e1aa3347 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.640047
Chicago Manual of Style (16th Edition):
Movsisyan, Levon. “Polyyne rotaxanes.” 2014. Doctoral Dissertation, University of Oxford. Accessed April 23, 2021.
http://ora.ox.ac.uk/objects/uuid:7f436a99-071f-4cc5-a4b5-5779e1aa3347 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.640047.
MLA Handbook (7th Edition):
Movsisyan, Levon. “Polyyne rotaxanes.” 2014. Web. 23 Apr 2021.
Vancouver:
Movsisyan L. Polyyne rotaxanes. [Internet] [Doctoral dissertation]. University of Oxford; 2014. [cited 2021 Apr 23].
Available from: http://ora.ox.ac.uk/objects/uuid:7f436a99-071f-4cc5-a4b5-5779e1aa3347 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.640047.
Council of Science Editors:
Movsisyan L. Polyyne rotaxanes. [Doctoral Dissertation]. University of Oxford; 2014. Available from: http://ora.ox.ac.uk/objects/uuid:7f436a99-071f-4cc5-a4b5-5779e1aa3347 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.640047
Universitat Politècnica de València
30.
Aparici Espert, María Isabel.
Photochemistry of 1,3-Dicarbonyl Compounds: DNA Photodamage vs. Photoprotection
.
Degree: 2018, Universitat Politècnica de València
URL: http://hdl.handle.net/10251/105782
► El objetivo principal de esta tesis es contrastar el papel de dichos compuestos 1,3-dicarbonilicos como agentes que dañan el ADN con respecto a su potencial…
(more)
▼ El objetivo principal de esta tesis es contrastar el papel de dichos compuestos 1,3-dicarbonilicos como agentes que dañan el ADN con respecto a su potencial fotoprotector.
Primero, 5,6-dihidropirimidinas han sido derivatizadas utilizando el grupo fotolábil t-Bu cetona con el fin de estudiar la generación de radicales en C5 en un medio no acuoso. Después, el estudio por fotólisis de destello láser en ACN de los derivados 1,3-dicarbonilicos diseñados da lugar a la detección de los supuestos radicales 5,6-dihidropirimidin-5-ilo. Su caracterización muestra especies transitorias de vida larga y están centrados a 400-420 nm o 350-400 nm para los derivados 5,6-dihidrouridina o 5,6-dihidrotimidina, respectivamente. Además, la generación de radicales también se ha evidenciado mediante experimentos de fluorescencia en estado estacionario mediante el uso de una sonda profluorescente (AAA-TEMPO) que atrapa el radical. Por lo tanto, la irradiación de los derivados fotolábiles del ácido nucleico en presencia de AAA-TEMPO produce un aumento de la emisión, de acuerdo con la captura del radical C5 por la sonda paramagnética. La formación del aducto se ha confirmado mediante UPLC-HRMS. Los datos experimentales se han corroborado con cálculos teóricos ab initio CASPT2 // CASSCF.
Segundo, otro derivado 1,3-dicarbonílico de la pirimidina se ha investigado. De hecho, el daño 5-formiluracilo (ForU) presenta características interesantes como potencial agente fotosensibilizador intrínseco del ADN. Por lo tanto, los estudios espectroscópicos revelan que ForU tiene una absorción en el rango UVA/UVB y también presenta un estado triplete excitado (3ForU *) con un tiempo de vida algunos micros y con una ET suficientemente alta como para fotosensibilizar la formación de los conocidos dímeros de pirimidina de tipo ciclobutano (CPDs) a través de una transferencia de energía triplete-triplete. Este proceso ha sido confirmado por medio de la síntesis de díadas modelo Thy-Thy y Cyt-Cyt, ya que su irradiación en presencia de ForU ha demostrado que producen CPDs. Asimismo, el estudio en ADN plasmídico permitió establecer la capacidad de ForU para inducir roturas de cadena simple y CPDs.
A continuación, se ha desarrollo una nueva estrategia para la fotoprotección de moléculas bioactivas aprovechando la reactividad fotoquímica del tautómero 1,3-dicetona de la avobenzona (AB), un filtro del UVA. Los compuestos seleccionados son dos fármacos antiinflamatorios no esteroideos de uso tópico con propiedades fotosensibilizantes, (S)-ketoprofeno (KP) y diclofenaco (DF). El tautómero dicetona de la AB contiene dos restos fenacilo, que es un grupo protector fotolábil muy establecido. Por lo tanto, un diseño juicioso de una díada profármaco/profiltro permite la fotoliberación del fármaco y de su protector, la AB. La viabilidad de esta liberación controlada de los ingredientes se verificó en diferentes disolventes con carácter dador de H y viscosidad para simular la formulación tópica. Además, los estudios de fotólisis de destello láser en EtOH permiten la…
Advisors/Committee Members: Lhiaubet, Virginie Lyria (advisor), Miranda Alonso, Miguel Ángel (advisor).
Subjects/Keywords: 1,3-dicarbonyl compounds;
Photochemistry;
Photophysics;
DNA;
Photodamage;
Photoprotection
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Aparici Espert, M. I. (2018). Photochemistry of 1,3-Dicarbonyl Compounds: DNA Photodamage vs. Photoprotection
. (Doctoral Dissertation). Universitat Politècnica de València. Retrieved from http://hdl.handle.net/10251/105782
Chicago Manual of Style (16th Edition):
Aparici Espert, María Isabel. “Photochemistry of 1,3-Dicarbonyl Compounds: DNA Photodamage vs. Photoprotection
.” 2018. Doctoral Dissertation, Universitat Politècnica de València. Accessed April 23, 2021.
http://hdl.handle.net/10251/105782.
MLA Handbook (7th Edition):
Aparici Espert, María Isabel. “Photochemistry of 1,3-Dicarbonyl Compounds: DNA Photodamage vs. Photoprotection
.” 2018. Web. 23 Apr 2021.
Vancouver:
Aparici Espert MI. Photochemistry of 1,3-Dicarbonyl Compounds: DNA Photodamage vs. Photoprotection
. [Internet] [Doctoral dissertation]. Universitat Politècnica de València; 2018. [cited 2021 Apr 23].
Available from: http://hdl.handle.net/10251/105782.
Council of Science Editors:
Aparici Espert MI. Photochemistry of 1,3-Dicarbonyl Compounds: DNA Photodamage vs. Photoprotection
. [Doctoral Dissertation]. Universitat Politècnica de València; 2018. Available from: http://hdl.handle.net/10251/105782
◁ [1] [2] [3] [4] [5] [6] [7] ▶
. 
Open Access Theses and Dissertations