Accelerated Interfacial Electron Transfer in Perovskite Solar Cell by Ammonium Hexachlorostannate Modification and fs-TAS Investigation

Organic-inorganic halide perovskite solar cells (PSCs) have received widespread attention due to their outstanding photovoltaic performance and straightforward preparation process. However, charge recombination at the interface is a crucial factor limiting further enhancement of the power conversion efficiency (PCE) of the PSCs. In this study, we report the interfacial modification between the electron transport layer and the perovskite film (PSK) using ammonium hexachlorostannate (AH) crystals synthesized via the room temperature spin-coating method. AH as an inorganic tin-based perovskite material, can passivate defects in the PSK and establish a better lattice match, thereby enhancing the quality and crystallinity of the PSK. Kelvin probe force microscopy results confirm that AH promotes the directional migration of photogenerated electrons. Femtosecond transient absorption spectroscopy results verify that AH effectively shortens the lifetime of electron extraction and facilitates interfacial electron transfer . Based on the benefits of AH modification, AH-based PSCs exhibit higher PCE and reduced hysteresis effect. Ammonium hexachlorostannate acts as an interfacial modifier between electron transport layer and perovskite film which can significantly accelerate the interfacial electron transfer.