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, PC₆₁BM is widely used as the electron transport layer (ETL) for inverted hybrid perovksite solar cells. Here we propose and demonstrate that Bi₂S₃, 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 Bi₂S₃ ETL with high conductivity. Our NiO/CH₃NH₃PbI₃/Bi₂S₃ solar cell achieved a device efficiency of 13%, which is comparable with our counterpart device using PC₆₁BM 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 Bi₂S₃ ETL. We believe thermally evaporated Bi₂S₃ is a promising ETL for inverted hybrid perovskite solar cells and worthy of further exploration.

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