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|Author||Burger, Jonadan Ando|
|Title||Bismuth ferrite sensitization of nanostructured titanium dioxide and/or zinc oxide-based for photovoltaic device applications|
Bismuth ferrite (BFO) is a ‘mid-range’ band gap, multiferroic (ferroelectric, antiferromagnetic) material of interest in numerous applications39,96,100-106. Though its use in photovoltaic applications has been investigated39,96,100-102,104,105 with interesting result, such a material has not yet been used as a photovoltaic sensitizer/thin absorber in sensitized solar cell (SSC) or extremely thin absorber solar cell (eta-SC) devices. A band gap (Eg~2.2-2.8eV) 40,100,103,105,117,139,147 within the visible light range (albeit high) makes BFO a potential candidate for such application. Moreover, BFO is ferroelectric (Ec ~500-600kV/cm, Pr = 60μC/cm2)100,159, which provides the material with an internal electric field (which can be directed/’poled’ towards one electrode or another in a(n) SSC/eta-device), which may provide an additional mechanism for either or both charge separation and transport.CuSCN/ZnO, CuSCN/TiO2, CuSCN/Bi-Fe-Zn-O/ZnO, CuSCN/BFO/TiO2 thin-film ‘sandwich-like’ structures were fabricated on transparent-conducting-oxide-glass (TCO) substrates, via combinations of electrodeposition and suspension or sol-gel (requiring ‘high temperature’ for crystallization) dip-coating, and characterized at various stages of production to assess material/phases present, optical absorbance characteristics, and preliminary electronic device performance. ‘High-temperature’ heat treatments in air or N2 of Bi-Fe-Zn-O/ZnO samples result in films yielding crystalline non-BFO phases, while O2 annealing of similar samples appear promising. BFO has been successfully crystallized on nearly-pure anatase TiO2 synthesized/deposited two ways, as well as on F:SnO2-glass. Moreover, BFO is found to enhance absorbency in at least a portion the visible portion of the electromagnetic spectrum. Such are promising signs that thin-absorber-PV devices based on either TiO2 or ZnO may be viable for development in the near future.
M.S., Materials Science and Engineering – Drexel University, 2010
|Subjects/Keywords||Materials science; Solar cells; Photovoltaic cells|
|Contributors||Spanier, Jonathan; College of Engineering; Drexel University|
|Country of Publication||us|