Dion-Jacobson 2D Perovskite 2AMPPbBr4 with Type II Band Alignment for Highly Sensitive X-Ray Detection

Abstract

2D hybrid perovskites have emerged as a promising alternative material to address the environmental stability and the ion-migration of the 3D perovskites for direct X-ray detector applications. Nevertheless, the X-ray detection performance of the 2D hybrid perovskites still lags because of its low X-ray attenuation ability and limited solubility for thick film deposition. Here, a high-performance X-ray detector in Dion-Jacobson 2D hybrid perovskite, 2(aminomethyl) pyridinium lead bromide (2AMPPbBr₄), is studied. 2AMPPbBr₄ exhibits an ultra-short interlayer distance of 3.43 Å, leading to high X-ray attenuation ability. Furthermore, DFT results indicate that 2AMPPbBr₄ exhibits type II band alignment between 2AMP²⁺ ligand and the [PbI₆]⁴⁻ layers, facilitating effective spatial separation of photo-generated carriers. The X-ray detector made of 2AMPPbBr₄ with an average thickness of 200 µm is realized via an improved drop-casting method. An improved X-ray sensitivity of 3933.88 µC Gy⁻¹ cm⁻² and a low detection limit of 4.17 nGy s⁻¹ is achieved. This work paves the way for high-performance X-ray detectors based on the emerging 2D perovskite materials.