Zero-Dimensional Lead-Free FA<sub>3</sub>Bi<sub>2</sub>I<sub>9</sub> Single Crystals for High-Performance X-ray Detection
Wei Li, Deyu Xin, Shujie Tie, Jiwei Ren, Siyin Dong, Lin Lei, Xiaojia Zheng, Yiying Zhao, Wen‐Hua Zhang
Abstract
Direct X-ray detectors based on metal halide perovskites and their derivatives exhibit high sensitivity and low limit of detection (LoD). Compared with three-dimensional (3D) hybrid lead halide perovskites, low-dimensional A 3 Bi 2 I 9 perovskite derivatives (A = Cs, Rb, NH 4, CH 3 NH 3 (MA)) present better stability, greater environmental friendliness, and comparable X-ray detection performance. Here, we report FA 3 Bi 2 I 9 (FA= CH(NH 2 ) 2 ) single crystals (SCs) as a new member of the A 3 Bi 2 I 9 series for X-ray detection, which were prepared by the nucleation-controlled secondary solution constant temperature evaporation (SSCE) method. Centimeter-sized FA 3 Bi 2 I 9 SCs show a full width at half-maximum (fwhm) of 0.0096°, which is superior to that of recently reported Cs 3 Bi 2 I 9 (0.058°) and MA 3 Bi 2 I 9 SCs (0.024°) obtained by inverse temperature crystallization (ITC). The as-grown FA 3 Bi 2 I 9 SC shows a large resistivity of 7.8 × 10 10 Ω cm and a high ion migration activation energy ( E a ) of 0.56 eV, which can guarantee a low noise level and good operational stability under a large external bias. The FA 3 Bi 2 I 9 SC detector exhibits a LoD of 0.2 μGy air s –1, a sensitivity of 598.1 μC Gy air –1 cm –2, and an X-ray detection efficiency of 33.5%, which are much better than those of the commercialized amorphous selenium detector. Results presented here will provide a new lead-free perovskite-type material to achieve green, sensitive, and stable X-ray detectors.