High-Performance Planar-Type Ultraviolet Photodetector Based on High-Quality CH₃NH₃PbCl₃ Perovskite Single Crystals

A hybrid perovskite MAPbCl₃ (MA = CH₃NH₃⁺) single crystal is considered to be one of the most viable candidates for the development of photodetectors because of its outstanding optoelectronic properties. However, the relatively lower crystalline quality of the reported MAPbCl₃ single crystals fabricated by the traditional one-step inverse temperature crystallization results in momentous degradation in the performance of their photodetectors. Here, we present a novel two-step temperature process to fabricate high-quality MAPbCl₃ single crystals, namely, lower temperature nucleation and higher temperature crystallization. These MAPbCl₃ single crystals present low defect density (∼7.9 × 10⁹ cm^-3) commensurate with the best-quality crystals of hybrid organic-inorganic lead halide perovskites reported so far. Moreover, a high-performance ultraviolet photodetector was demonstrated on MAPbCl₃ single crystals. At 30 V, the peak responsivity at 415 nm of the photodetector is as high as 3.73 A W^-1 (light intensity = 1 mW cm^-2), ∼2-3 orders of magnitude higher than that of the previously reported MAPbCl₃ photodetectors. Meanwhile, the device has an ultrafast response speed with a rise time of 130 ns, which is one of the shortest values of MAPbX₃-based photodetectors. Our findings open a new way to obtain high-quality perovskite single crystals and their high-performance photodetectors.