Thin Film Photovoltaic Options – an Overview

ABSTRACTSignificant deployment of the promising option of photovoltaics for energy will require cost-effective technologies that compete effectively with conventional sources. One such option utilizes thin films of a variety of photovoltaic materials. These thin films must be manufacturable in large quantities, and they must have high performance and acceptable reliability. Amorphous silicon (a-Si) was the first successfully demonstrated thin film to be widely adopted by industry. This material is already used to power a larger number of such consumer products as calculators, watches, and battery chargers. Recently, a-Si solar cells have been scaled up to large-area modules for power applications. Large fields of these modules have been deployed by utility companies for their evaluation. Polycrystalline thin films such as copper indium diselenide (CIS) and cadmium telluride (CdTe) have recently shown promise in following the path of a-Si. High-efficiency, large-area submodules have been successfully tested. By combining these materials in hybrid combinations, researchers have demonstrated much higher efficiencies. Even higher efficiencies have been demonstrated with more conventional materials such as silicon and gallium arsenide in thin-film form. Such devices have a high degree of acceptability because of their successful application for power uses in their non-thin-film form. Extensive examples are given to demonstrate the technical viability of these photovoltaic approaches for possible use in utility-scale power plants and in other near-term, highvalue markets.