ADVANCES IN CUINSE2 AND CDTE THIN-FILM SOLAR-CELLS

Research on CuInSe and CdTe thin film solar cells is discussed. CuInSe2 Was deposited by selenization of Cu/In layers and was used to make a 10% efficient CuInSe2/(CdZn)S cell. Characterization of the reaction mechanisms is described. The open-circuit voltage V(oc) of CuInSe2/(CdZn)S cells is dominated by recombination in the space charge region, so increasing the band gap or decreasing the width of this region should increase V(oc). Increasing the band gap with a thin Cu(InGa)Se2 layer at the CuInSe2 Surface has demonstrated increased V(oc) with collection out to the CuInSe2 band gap. A post-deposition treatment and contacting process for evaporated CdS/CdTe cells was developed and high efficiency cells were made. Several steps in the process, including a CdCl2 coating, a 400-degrees-C heat treatment, and a contact containing copper are critical. ZnTe films were deposited from an aqueous solution as a contact to CdTe.