Zero‐Dimensional Lead‐Free Perovskite Single Crystals for the Sensitive Detection of Visible Light and X‐Rays

The excellent performance and facile fabrication process of perovskite semiconductor materials make them highly promising candidates in the field of optoelectronic devices. Whether for visible light or X-rays, detectors with low detection limits can better identify weak light signals, significantly reducing the intensity of the received light source during device operation. In particular, for X-ray detectors, reducing X-ray dosage can greatly enhance the safety of X-ray imaging technology. This work develops detectors with low detection limit based on zero-dimensional (0D) MA₃Bi₂I₉ single crystals. The anisotropy of MA₃Bi₂I₉ and its influence on the detector's performance were investigated in detail. Detectors perpendicular to the (001) crystal plane have better weak light detection capability and require significantly less light intensity compared to devices parallel to the (001) crystal plane. X-ray detector with a limit of detection (LoD) of 0.68 nGy_air s^-1 and sensitivity of 5072 μC Gy_air ^-1 cm^-2 was obtained. The present study offers comprehensive insights into the operational mechanism of layered perovskites, which can provide valuable guidelines for future designs and fabrications of highly sensitive photo and X-ray detectors.