Surface passivated halide perovskite single-crystal for efficient photoelectrochemical synthesis of...

Halide perovskite single-crystals have recently been widely highlighted to possess high light harvesting capability and superior charge transport behaviour, which further enable their attractive performance in photovoltaics. However, their application in photoelectrochemical cells has not yet been reported. Here, a methylammonium lead bromide MAPbBr₃ single-crystal thin film is reported as a photoanode with potential application in photoelectrochemical organic synthesis, 2,5-dimethoxy-2,5-dihydrofuran. Depositing an ultrathin Al₂O₃ layer is found to effectively passivate perovskite surface defects. Thus, the nearly 5-fold increase in photoelectrochemical performance with the saturated current being increased from 1.2 to 5.5 mA cm^-2 is mainly attributed to suppressed trap-assisted recombination for MAPbBr₃ single-crystal thin film/Al₂O₃. In addition, Ti³⁺-species-rich titanium deposition has been introduced not only as a protective film but also as a catalytic layer to further advance performance and stability. As an encouraging result, the photoelectrochemical performance and stability of MAPbBr₃ single-crystal thin film/Al₂O₃/Ti-based photoanode have been significantly improved for 6 h continuous dimethoxydihydrofuran evolution test with a high Faraday efficiency of 93%.