Temperature‐Gradient‐Controlled Method Enabling Shape Control of 2D Perovskite Single Crystals for Photodetection

Abstract

2D hybrid organic–inorganic lead halide perovskites have been reported as promising photodetection active semiconductor materials due to their excellent photoelectric properties and stability. However, the solution growth of 2D crystal materials is affected adversely by narrow process windows, low process reproducibility, and small crystal sizes. Herein, a temperature‐gradient‐controlled method to grow high‐quality 2D perovskite crystals on the order of centimeters is developed. Using this new method, BA2PbI4 and mixed‐cation BA2FAxMA1−xPb2I7 crystals are produced with shape control and improved quality at the bottom of the precursor solution. Subsequently, their photoelectric responses are investigated comprehensively. Photodetectors based on these single crystals exhibit outstanding performances, affording 10−11 A dark current, > 103 on–off ratio, ≈10 mA W−1 responsivity, excellent stability, and linear photoresponse. Moreover, the annealing of crystals effectively reduces the dark current of the detectors. The mixed‐cation BA2FA0.4MA0.6Pb2I7 crystal demonstrates improved photoelectric response and a significant change in morphology.