Photovoltaic properties of Cu(In,Ga)Se/sub 2/ thin film solar cell fabricated by coevaporation process

Thin film solar cells based on Cu(In,Ga)Se/sub 2/ films were fabricated, and their junction and photovoltaic properties were investigated. Ga in CuInSe/sub 2/ thin films formed by the so-called "bilayer process" was incorporated homogeneously. The fabricated cell structure was glass/Mo/Cu(In,Ga)Se/sub 2//CdS/ZnO/ITO(/MgF/sub 2/). The incorporation of Ga into CuInSe/sub 2/ films up to about 20 mol% improved the photovoltaic performance. From the study of photoluminescence, capacitance-voltage and current-voltage characteristics, it was clarified that the incorporation of Ga not only widened the bandgap energy, but also played an important role in the effect which yields hole concentration. The best cell with an AR-coating (MgF/sub 2/) exhibited an efficiency of 15.2%; Jsc=33.9 mA/cm/sup 2/, Voc=0.616 V, FF=0.730. The device performance can be improved by the development of the film with higher hole concentration, keeping the crystalline quality.