Roberson, Luke Bennett.
Understanding organic thin film properties for microelectronic organic field-effect transistors and solar cells.
Degree: PhD, Chemistry and Biochemistry, 2005, Georgia Tech
The objective of this work is to understand how the thin film characteristics of p-type organic and polymer semiconductors affect their electronic properties in microelectronic applications. To achieve this goal, three main objectives were drawn out: (1) to create single-crystal organic field-effect transistors and measure the intrinsic charge carrier mobility, (2) to develop a platform for measuring and depositing polymer thin films for organic field-effect transistors, and (3) to deposit polythiophene thin films for inorganic-organic hybrid solar cells and determine how thin film properties effect device performance.
Pentacene single-crystal field-effect transistors (OFETs) were successfully manufactured on crystals grown via horizontal vapor-phase reactors designed for simultaneous ultrapurification and crystal growth. These OFETs led to calculated pentacene field-effect mobility of 2.2 cm2/Vs. During the sublimation of pentacene at atmospheric pressure, a pentacene disporportionation reaction was observed whereby pentacene reacted with itself to form a peripentacene, a 2:1 cocrystal of pentacene:6,13-dihydropentacene and 6,13-dihydropentacene. This has led to the proposal of a possible mechanism for the observed disproportionation reaction similar to other polyaromatic hydrocarbons, which may be a precursor for explaining the formation of graphite.
Several silicon-based and PET-based field-effect transistor platforms were developed for the measurement of mobility of materials in the thin film state. These platforms were critically examined against one another and the single-crystal devices in order to determine the optimal device design for highest possible mobility data, both theoretically based on silicon technology and commercially based on individual devices on flexible substrates. Novel FET device designs were constructed with a single gate per device on silicon and PET as well as the commonly used common-gate device. It was found that the deplanarization effects and poor gate insulator quality of the individual gate devices led to lower overall performance when compared to the common gate approach; however, good transistor behavior was observed with field modulation.
Additionally, these thin films were implemented into inorganic-organic hybrid and purely organic solid-state photovoltaic cells. A correlation was drawn between the thin film properties of the device materials and the overall performance of the device. It was determined that each subsequent layer deposited on the device led to a planarization effect, and that the more pristine the individual layer, the better device performance. The hybrid cells performed at VOC = 0.8V and JSC = 55A/cm2.
Advisors/Committee Members: Laren Tolbert (Committee Chair), Art Janata (Committee Member), David Collard (Committee Member), Marcus Weck (Committee Member), Mohan Srinivasarao (Committee Member), Uwe Bunz (Committee Member).
Subjects/Keywords: Transistors; Thin films; Solar cells; OFET; Organic semiconductors; Field-effect transistors; Thin film transistors; Solar cells
to Zotero / EndNote / Reference
APA (6th Edition):
Roberson, L. B. (2005). Understanding organic thin film properties for microelectronic organic field-effect transistors and solar cells. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/7629
Chicago Manual of Style (16th Edition):
Roberson, Luke Bennett. “Understanding organic thin film properties for microelectronic organic field-effect transistors and solar cells.” 2005. Doctoral Dissertation, Georgia Tech. Accessed March 06, 2021.
MLA Handbook (7th Edition):
Roberson, Luke Bennett. “Understanding organic thin film properties for microelectronic organic field-effect transistors and solar cells.” 2005. Web. 06 Mar 2021.
Roberson LB. Understanding organic thin film properties for microelectronic organic field-effect transistors and solar cells. [Internet] [Doctoral dissertation]. Georgia Tech; 2005. [cited 2021 Mar 06].
Available from: http://hdl.handle.net/1853/7629.
Council of Science Editors:
Roberson LB. Understanding organic thin film properties for microelectronic organic field-effect transistors and solar cells. [Doctoral Dissertation]. Georgia Tech; 2005. Available from: http://hdl.handle.net/1853/7629