Low-Temperature-Processed Amorphous Bi2S3 Film as an Inorganic Electron Transport Layer for Perovskite Solar Cells

Organic–inorganic hybrid perovskite solar cells have attracted great attention due to their unique properties and rapid increased power conversion efficiency. Currently, PC 61 BM is widely used as the electron transport layer (ETL) for inverted hybrid perovksite solar cells. Here we propose and demonstrate that Bi 2 S 3, a ribboned compound with intrinsic high mobility and stability, could be used as the ETL for perovksite solar cells. Through a simple thermal evaporation with the substrate kept at room temperature, we successfully produced a compact and smooth amorphous Bi 2 S 3 ETL with high conductivity. Our NiO/CH 3 NH 3 PbI 3 /Bi 2 S 3 solar cell achieved a device efficiency of 13%, which is comparable with our counterpart device using PC 61 BM as the ETL. Moreover, our device showed much improved ambient storage stability due to the hydrophobic and hermetic encapsulation of the perovskite layer by the Bi 2 S 3 ETL. We believe thermally evaporated Bi 2 S 3 is a promising ETL for inverted hybrid perovskite solar cells and worthy of further exploration.