Huawei Yang, Zhou Lan, Jianbo Wu, Zeyu Chen, Panpan Yu, Zeng‐Kui Zhu, Haodong Ge, Yue Wang, Wenhui Wu, Ying Zeng, Hui‐Ping Xiao, Junhua Luo
ABSTRACT Dion‐Jacobson (DJ) hybrid perovskites are considered as highly promising X‐ray detection materials due to their high stability and short interlayer spacing. However, the large‐scale commercial development of these materials is challenged due to severe ion migration at high voltage and lead toxicity. Here, we successfully obtained a DJ‐type polar lead‐free green hybrid perovskite (4AMPY) 2 AgBiBr 8 ( 1 ) by inserting 4‐aminomethylpyridine (4AMPY) aromatic diamine into 3D Cs 2 AgBiBr 6 , and achieved efficient and stable self‐powered X‐ray detection. Specifically, owing to the insertion of 4AMPY, 1 crystallizes in polar space group P 2 1 and exhibits a significant bulk photovoltaic effect. Additionally, strong hydrogen‐bonding interactions between 4AMPY and adjacent inorganic layers lead to an ultranarrow interlayer spacing of 3.09 Å. Meanwhile, the enhanced electron cloud density in aromatic diamines improves the charge transfer channel of 1 and enhances its X‐ray detection performance. Therefore, among all DJ‐type lead‐free hybrid perovskites, 1 achieves record‐breaking sensitivities of 661.4 and 9465.2 µC Gy −1 cm −2 at 0 and 100 V, respectively. Importantly, 1 exhibits excellent storage stability, with its sensitivity remaining at 97.5% (0 V) and 96.6% (100 V) of the initial value after three months. This work will greatly promote the development of polar DJ‐type lead‐free perovskite‐based self‐powered X‐ray detectors.