19.7% Efficient CdSe/CdTe Solar cells Fabricated using High-Vacuum CSS System

The close-spaced sublimation (CSS) deposition system has gained significant interest from researchers due to its low cost, high-temperature processing capabilities, ease of fabrication, and high deposition rate. In this study, we used a high-vacuum CSS system to perform various heat treatments on CdSe films, followed by the deposition of CdTe without breaking the high vacuum. Formation of tellurium oxide species on the heat-treated CdSe surface facilitated the growth of larger CdTe grains was observed. CdTe solar cells fabricated using heat-treated CdSe films and copper thiocyanide as the back contact material achieved a device efficiency of 19.7%, with an open-circuit voltage (Voc) of 857 mV, a short-circuit current (Jsc) of 28.9 mA/cm², and a fill factor (FF) of 79.6%.