Highly Stable and Sensitive (PEA)₂PbBr₄/CsPbBr₃ Single-Crystal Heterojunction X-Ray Detector with Ultra-Low Detection Limit

Metal halide perovskite (MHP) single crystals have shown great potential for high-performance X-ray detection due to their excellent carrier transport properties, tunable optical bandgap, and low-temperature fabrication process. However, 3D perovskite single crystals suffer from severe ion migration, limiting the stability and sensitivity of X-ray detectors. Herein, a lowing temperature crystallization (LTC) method for liquid-phase epitaxial growth of 2D (PEA)(2)PbBr4 single-crystal (SC) film on 3D CsPbBr3 substrate is demonstratedand a 2D/3D (PEA)(2)PbBr4/CsPbBr3 SC heterojunction is successfully constructed. The epitaxial (PEA)(2)PbBr4 layer shows a pronounced passivation effect on CsPbBr3 SC with a low trap density of 2.27 x 10(10) cm(-3). As such, the prepared 2D/3D heterojunction X-ray detector achieves a record-low detectable dose rate of 3.05 nGy(air) s(-1) and high sensitivity of 34496 mu C Gy(air)(-1) cm(-2) in 120 keV hard X-ray detection, with a largely suppressed dark current drift of 2.49 x 10(-4) nA cm(-1) s(-1) V-1. In addition, the heterojunction detector exhibits a self-driven sensitivity of 44 mu C Gy(air)(-1) cm(-2) due to its built-in electric field. This work provides a simple strategy to controllable construct 2D/3D MHP SC heterojunction with excellent optoelectronic characteristic, which is conducive to promoting the development of MHP SC X-ray detectors and other optoelectronic devices.