Ion-exchange-induced slow crystallization of 2D-3D perovskite thick junctions for X-ray detection and imaging

Metal-halide perovskites have recently emerged as promising candidates for next-generation X-ray detectors, mainly benefiting from their low-temperature solution processability, chemical versatility, low cost, and excellent and tunable optoelectronic properties. However, the fabrication of perovskite thick junctions is very challenging, particularly for solution-processed thick photodiodes. Here, we report an ion-exchange strategy to prepare two-dimen-sional (2D)-3D perovskite thick films for directly detecting X-rays. This approach provides a facile and generic fabrication of high -quality perovskite films with various perovskite precursors, achieving uniform morphology, tunable thickness, and vertically monolithic crystal phase. The dynamic processes of the ion ex-change were fully characterized and studied with multiple in situ and ex situ techniques, e.g., photoluminescence spectroscopy and X-ray diffraction. After optimization, record-high X-ray sensitivity of 1.36 3 10(4) mC Gyair(-1) cm(-2) and ultra-low detection limit of 4.2 nG(yair) s(-1) were achieved based on the optimized (BA(2)PbBr(4))(0.5)-FAPbI3 detectors, demonstrated along with 32 3 32 pixel prototypical photodetector arrays.

Automated summary

Metal-halide perovskites have great potential as next-generation X-ray detectors due to their low cost, processability, and tunable optoelectronic properties. Researchers have developed a ion-exchange strategy to fabricate two-dimensional (2D)-3D perovskite thick films for X-ray detection, achieving high sensitivity and low detection limit.