X-ray Detector with Ultra-low Detection Limit based on Bulk Two-dimensional Perovskite PEA2PbBr4 Single Crystals Grown in HBr Solution

Abstract

Achieving lower detection limit is always crucial for X-ray detectors in medical imaging. Two-dimensional (2D) perovskite is a superior candidate material for X-ray detection due to the high bulk resistivity, excellent environmental stability, and negligible ion migration under high bias. However, the reported detection limit of 2D perovskite X-ray detectors still apparently lags behind that of 3D analogies due to the difficulty in growth of high-quality bulk 2D perovskite single crystals (SCs). Herein, we demonstrate an X-ray detector with ultra-low detection limit based on high-quality bulk PEA₂PbBr₄ SCs grown in HBr solution for the first time. According to the solubility difference of reactants, a slowly varying nucleation curve for precursor solution is designed to stabilize growth rate and reduce defect density during crystal growth. The fabricated Au/PEA₂PbBr₄/Au detector shows a low noise level as 10^-5 nA Hz^-1/2 and an ultra-low dark current drift of 6.6 × 10^-7 pA cm^-1 V^-1 s^-1. Together with a commendable hole lifetime of 2.76 μs and hole mobility-lifetime product of 1.0 × 10^-3 cm² V^-1, the produced detector exhibits a high sensitivity of 2,998 μC Gy_air s^-1 cm^-2 and a record-low detection limit of 0.79 nGy_air s^-1. The current work would be beneficial for the development of next generation medical imaging.