Nucleation Engineering in Sprayed MA<sub>3</sub>Bi<sub>2</sub>I<sub>9</sub> Films for Direct-Conversion X-ray Detectors
Deyu Xin, Siyin Dong, Min Zhang, Shujie Tie, Jiwei Ren, Lin Lei, Ping Yu, Jianguo Zhu, Yiying Zhao, Xiaojia Zheng
Abstract
Metal halide perovskite and its derivatives show great promise in X-ray detection. However, large-scale fabrication of high-quality thick perovskite films is still full of challenges due to the complicated crystal nucleation process that always introduces lots of cracks or pinholes in the final perovskite film. Here, a MA3Bi2I9 film was fabricated by the cost-effective, scalable spraying process, and MACl was used as an additive to effectively tune the crystallization process. As a result, a dense MA3Bi2I9 film constituted by large grains was obtained, which has a high carrier mobility of ∼1 cm2 V–1 s–1 and a large activation energy (Ea) for ion migration of 0.91 eV. Thanks to the outstanding optoelectronic characteristics, X-ray detectors with a configuration of ITO/MA3Bi2I9/Au show a sensitivity of 35 μC Gyair–1 cm–2 and a limit of detection (LoD) of 0.14 μGyairs–1, which is outstanding compared with commercial α-Se detectors.