Adjustable Positive-Negative Signal in Self-Driven Photodetector based on Cubic CH3NH3PbI3 Large Single Crystal

In this study, for the first time, self-driven photodetector based on cubic CH₃NH₃PbI₃ large single crystal (C-MAPbI₃ LSC) with adjustable positive-negative signal is fabricated. The preparation of MAPbI₃ large single crystal (MAPbI₃ LSC) is realized by the method of growth-drop-growth (GDG). The band gap of MAPbI₃ single crystals with Pm-3m (221) space group (6.134×6.134×6.134 Å, 90.00 x 90.00 x 90.00) is 1.58 eV. CH₃NH₃⁺ cation is orientation-disorder within the perovskite cubo-octahedral cavity. The photocurrent density at 803 nm of the C-MAPbI₃ LSC photodetector under different bias voltages is the highest under different wavelength. The responsivities (R), response time, external quantum efficiencies (EQE) and the detectivity (D) for C-MAPbI₃ LSC photodetector at 803 nm wavelength with 1 W m^-2, respectively, is 508.7 µA/mW, 0.1338 ms, 79.6% and 8.64*10¹¹ Jones. Notably, the C-MAPbI₃ LSC photodetector can be self-driven under 0 V bias voltage, in particular, the positive and negative values of the photocurrent can be adjusted. The proposed mechanism of poling inducing built-in potential is explained adjustable positive-negative signal in self-driven photodetector based on cubic CH₃NH₃PbI₃ large single crystal.