CIS-Type PV Device Fabrication by Novel Techniques: Phase II Annual Technical Report, 1 July 1999 -- 30 June 2000

The R&D program at ISET is centered on development of a novel, dispersion-based route to the deposition of precursor thin films that are converted to CIS-type absorbers through high temperature reactions at or close to atmospheric pressure. The goal of the current research program at ISET is to bring a non-vacuum processing route for CIS closer to commercialization by improving the deviceefficiency through an increase in absorber bandgap. The basic processing approach involves first synthesizing a powder containing the oxides of copper, indium and gallium. A dispersion (ink) is prepared from the starting powder by mechanical milling or sonication. This ink is then deposited onto the glass/moly substrate as a thin precursor (3-4?m) and converted to a metallic alloy film byreaction in a hydrogen atmosphere. Controlled synthesis of starting powders and proper reduction results in reasonably smooth, metallic precursor films similar to those produced by sputtering or evaporation. From this point the processing is similar to that in the other two-stage techniques, with the metallic film being reacted in H2Se to form the final photovoltaic absorber, followed by CdS andTCO deposition.