Liquid-Phase Growth and Optoelectronic Properties of Two-dimensional Hybrid Perovskites CH3NH3PbX3 (X=Cl, Br, I)

The hybrid perovskite CH3NH3PbX3 (X= Cl, Br, I) is a promising material for developing novel optoelectronic devices. Owing to the intrinsic non-layered crystal structure, it remains challenging to synthesize two-dimensional (2D) single-crystalline CH3NH3PbX3 with a nanoscale thickness. Here, we report a bottom-up approach to fabricate large-size CH3NH3PbX3 2D crystals via a liquid-phase Growth on a mica substrate. The strong potassium-halogen interactions at the perovskite/mica interface lower the interface energy, driving the striking in-plane growth of perovskite. The grown 2D CH3NH3PbBr3 crystal was characterized as 8 nm in thickness and hundreds of micrometers in lateral size. A weak exciton binding energy was crucial for improving the photoelectric performances of 2D CH3NH3PbBr3. The visible-light photodetector, with a metal/insulator/perovskite configuration, was finally achieved with a photoresponsivity of 126 AW-1 and a bandwidth exceeded 80 kHz. Our works have proved the liquid-phase growth on mica was a controllable method to grow 2D hybrid perovskites CH3NH3PbX3, which could facilitate both the device application and fundamental investigation.