Photovoltaic structures using thermally evaporated SnS and CdS thin films

Polycrystalline tin sulfide thin films were prepared by thermal evaporation technique. The films grown at substrate temperature of 300 °C had an orthorhombic crystal structure with strong preferred orientation along (111) plane. Electrical resistivity of the deposited films was about 32.5 Ω cm with a direct optical band gap of 1.33 eV. Carrier concentration and mobility of charge carriers estimated from the Hall measurement were found to be 6.24 × 1015 cm− 3 and 30.7 cm2V− 1 s− 1 respectively. Heterojunction solar cells were fabricated in superstrate configuration using thermally evaporated SnS as an absorber layer and CdS, In:CdS as window layer. The resistivity of pure CdS thin film of a thickness of 320 nm was about 1-2 Ω cm and was reduced to 40 × 10− 3 Ω cm upon indium doping. The fabricated solar cells were characterized using solar simulator. The solar cells with indium doped CdS window layer showed improved performance as compared to pure CdS window layer. The best device had a conversion efficiency of 0.4% and a fill factor of 33.5%.