Emerging trends in sulfide and selenide-based low-cost thin film solar cells

Binary metal sulfides and selenides are promising semiconductors for thin film solar cells because these earth abundant low-cost absorbers can circumvent the upscaling limitations of commercial CdTe and chalcopyrite devices. In this chapter, recent technological developments in Sb2S3, SnS, Cu2S, and PbS thin film solar cells are reviewed. For each sulfide absorber, the heterojunction device structure, absorber deposition method, postdeposition processing, and factors limiting photovoltaic performance are discussed in detail. For Sb2S3, the highest device power conversion efficiency (PCE) is 7.1% while PbS colloidal quantum dot devices have attained higher PCE at 10.19%. Sb2Se3 thin film solar cell with PCE of 7.6% can be fabricated by vapor transport deposition. The challenges and passivation solutions for high PCE in chalcogenide thin film solar cells are highlighted. Finally, emerging cubic π-SnS, π-GeS, and π-SnSe semiconductors with application potential in photovoltaics are briefly described.