Nucleation Engineering in Sprayed MABiI Films for Direct-Conversion X-ray Detectors.

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 MABiI 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 MABiI film constituted by large grains was obtained, which has a high carrier mobility of ∼1 cm V s and a large activation energy () for ion migration of 0.91 eV. Thanks to the outstanding optoelectronic characteristics, X-ray detectors with a configuration of ITO/MABiI/Au show a sensitivity of 35 μC Gy cm and a limit of detection (LoD) of 0.14 μGys, which is outstanding compared with commercial α-Se detectors.