Aqueous Sn-S Complex Derived Electron Selective Layer for Perovskite Solar Cells

A novel aqueous Sn-S complex solution was applied as precursor to fabricate SnO2 electron selective layers (ESLs) for the hybrid perovskite solar cells (PSCs). The tin and sulfur powder were directly dissolved in a (NH4)2S water solution to form Sn-S precursor. After depositon and annealing, the SnO2 film was formed, presenting as a low cost and enviromental friendly method for preparation of ESL. The films showed excellent transmittance at visible wavelength range. Moreover, the method exhibited high compatibility for doping using Cu, Cd, Li, and Zn elements. Zn doping (0.05 M) in the as-prepared SnO2 ESL significantly improved perovskite solar cells (PSCs) performance. The highest PCE of 13.17% was achived with 15% enhancement compared to that of undoped SnO2 ESL samples. TiCl4 modifications on SnO2 film improved photovoltaic performance to 14.45%, but resulted in the poor long-term stability, around 80% more degredation than that of PSCs based on Zn-doped SnO2 films.