Impurity PbCO₃ from Low-Purity Raw Material Improves MAPbBr₃ Single-Crystalline X-ray Detectors

Perovskite single crystals have been found to exhibit excellent X-ray detection and imaging performance. High-purity raw materials have generally been considered a prerequisite to guarantee crystal quality and device performance, which may lead to higher costs. However, we found that higher quality MAPbBr3 single crystals can be obtained from low-purity lead bromide (PbBr2). This is attributed to the presence of impurity lead carbonate (PbCO3) in the raw material. PbCO3 facilitates the suppression of crystal defects, leading to higher quality crystals. With the addition of a small amount of PbCO3 to high-purity PbBr2 raw material, MAPbBr3 single crystals grow with a smoother surface, improved uniformity, and lower defect concentrations. The single crystal becomes more intrinsic. The product of carrier mobility and lifetime increases to 1.3 × 10–2 cm2 V–1. With the addition of PbCO3, the detector sensitivity is about twice as high and the lowest detection limit is approximately 300 times lower, down to 20 nGyair/s. This work reveals the key factors for preparing high-quality perovskite single crystals using low-cost, low-purity raw materials, providing a new approach for producing high-yield perovskite single crystals.