Suppression of Ionic and Electronic Conductivity by Multilayer Heterojunctions Passivation Toward Sensitive and Stable Perovskite X‐Ray Detectors

• Published in: Advanced functional materials Vol. 33; no. 35
• Main Authors: Han, Mingyue, Xiao, Yingrui, Zhou, Chao, Xiao, Zijie, Tan, Wenyan, Yao, Guowei, Wu, Xiaoxue, Zhuang, Renzhong, Deng, Shiming, Hu, Qi, Yang, Yuxuan, Tang, Zhaoheng, Zhou, Xunsheng, Lin, Haobo, Liang, Huili, Lin, Shenghuang, Mei, Zengxia, Wang, Cailin, Chen, Qi, Zhang, Wei, Jiang, Yan
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.08.2023
• Subjects: Bromine; Crystal defects; Dark current; Detectors; Electric fields; electronic and ionic conductivity; Heterojunctions; Ion currents; Ions; Materials science; multilayer heterojunctions; Multilayers; Passivity; perovskite X‐ray detectors; Perovskites; Radiation dosage; Sensitivity; Sensors; Single crystals; Stability
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202303376

Organic‐inorganic hybrid perovskites are promising candidates for direct X‐ray detection and imaging. The relatively high dark current in perovskite single crystals (SCs) is a major limiting factor hindering the pursuit of performance and stability enhancement. In this study, the contribution of dark current is disentangled from electronic (σe) and ionic conductivity (σi) and shows that the high σi dominates the dark current of MAPbBr3 SCs. A multilayer heterojunctions passivation strategy is developed that suppresses not only the σi by two orders of magnitude but also σe by a factor of 1.6. The multilayer heterojunctions passivate the halide vacancy defects and increase the electron and hole injection barrier by inducing surface p‐type doping of MAPbBr3. This enables the MAPbBr3 SC X‐ray detectors to obtain a high sensitivity of 19 370 µC Gyair−1 cm−2 under a high electric field of 100 V cm−1, a record high sensitivity for bromine self‐powered devices, and a low detection limit of 42.3 nGyair s−1. The unencapsulated detectors demonstrate a stable baseline after storage for 210 days and outstanding operational stability upon irradiation with an accumulated dose of up to 1944 mGyair. A multilayer heterojunctions interface passivation strategy is developed to simultaneously reduce the ionic and electronic conductivity of organic–inorganic hybrid perovskite single crystals. The MAPbBr3 perovskite X‐ray detectors achieve high sensitivity of 19 370 µC Gyair−1 cm−2, low detection limit, negligible baseline drift after 210 days and outstanding irradiation stability with an accumulated dose equaling 9720 times posteroanterior chest examinations.