Metastable Zone Engineering With Excess Halide for Low-Defect MAPbBr3 Single Crystals with Ultra-Low X-Ray Detection Limit

초록

MAPbBr3 single crystals (MPB SCs) are promising materials for X-ray detection; however, their use in low-dose imaging is limited by high dark current, low detectability, and noise that degrades image clarity. Under X-ray irradiation, where electron-hole pair generation is inherently low, suppressing defects is critical to minimize losses and maximize charge collection. In this study, metastable zone engineering is employed by tuning the MABr:PbBr2 ratio during inverse temperature crystallization (ITC) to produce defect-suppressed MPB SCs. Excess MABr broadens and stabilizes the metastable zone, reducing nucleation events and enabling the growth of large, high-crystallinity MPB SCs exceeding 10 mm within 11 h. These crystals exhibit electronic properties closer to intrinsic behavior, with prolonged carrier lifetimes of 371 ns and an enhanced mobility-lifetime (& micro;tau) product of 3.43 & times; 10-3 cm2 V-1. Photoluminescence spectra reveal a distinct secondary peak from photon recycling, with intensity 1.25 times greater than the band-edge peak, indicating efficient photon reabsorption due to reduced non-radiative losses. Devices fabricated from excess MPB SCs achieve a record-low detection limit of 0.47 nGy s-1, high sensitivity (6.117 & times; 103 & micro;C Gyair -1 cm-2), and high-resolution X-ray imaging, demonstrating strong potential for advanced medical and industrial applications.

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