Low-temperature electrodeposited crystalline SnO₂ as an efficient electron-transporting layer for conventional perovskite solar cells

Tin oxide (SnO₂) has recently attracted significant research interest for its role functioning as an efficient electron-transporting layer (ETL) due to its higher charge mobility than the commonly used titanium oxide (TiO₂) for realizing high-performance perovskite solar cells (PVSCs). However, it is still challenging to develop a facile, low-temperature solution-based (<100 ^oC) processing method to synthesize crystalline SnO₂ with desirable charge mobility, which can facilitate its widespread applications in flexible optoelectronic devices. In this work, we utilize an electrochemical deposition technique to prepare SnO₂ films at a reduced temperature below 100 ^oC. The electrodeposition endows the SnO₂ film with high crystallinity and conductivity in addition to high transparency across the visible spectrum. Efficient photoluminescence (PL) quenching is observed in the bi-layered SnO₂/CH₃NH₃PbI₃ film, manifesting its efficient electron extraction capability from perovskite. Consequently, a conventional n-i-p PVSC using this electrodeposited SnO₂ ETL shows a high PCE of 13.88% with negligible hysteresis. This work demonstrates a low-temperature solution-based preparation route for making crystalline SnO₂ and its potential for application in large-scale PVSC production.