Biphasic Liquid–Liquid Interface Limit Architecture of High-Quality Perovskite Single-Crystal Sheets for UV Photodetection

Thin organic-inorganic MAPbX3 perovskite single-crystal sheets have become the hotspot of smart photodetectors because of their low number of trap states, high carrier mobility, long diffusion length, and effective light-receiving area. However, MAPbX3 single crystals are so fragile that single-crystal perovskite sheets with a thickness of ≤100 μm are hard to obtain by cutting. Thin single-crystal MAPbX3 sheets were synthesized by the biphasic liquid-liquid interface limit method with dimethicone/DMSO biphasic films and could be obtained with an adjustable thickness of 1-50 μm and improved crystal quality of the perovskite sheets. The thin MAPbX3 single-crystal sheet-based photodetector exhibits a superior responsivity of 0.88 A W-1, an external quantum efficiency of 276.8%, and an ultrahigh detectivity of 2.26 × 1011 Jones under 395 nm irradiation at 3 V. These values are more than 500% as high as those of the bulk-crystal-based photodetector. In particular, the sheet-based photodetector could retain long-time stability after 4200 on-off cycles.