Li Ruiqing, Wu Jianbo, Zhu Zeng-Kui, Geng Yaru, Li Xinling, Wang Yifei, Xu Bohui, Lin Zheshuai, Luo Junhua
State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences, Fuzhou Fujian 350002 P. R. China.
Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology School of Chemistry and Chemical Engineering Liaocheng University Liaocheng Shandong 252000 China.
Small Sci. 2025 Mar 11;5(5):2400508. doi: 10.1002/smsc.202400508. eCollection 2025 May.
Lead-free ABiI-type perovskites demonstrate excellent performance in direct X-ray detection owing to their high bulk resistivity and reduced ion migration. However, the reported centrosymmetric ABiI can only operate with external voltage, inevitably resulting in energy consumption and bulky monolithic circuits, limiting their further development. Herein, exploiting the methylhydrazine (MHy) cation with 2 lone-pair electrons (LPEs), a chiral-polarity perovskite MHyBiI are obtained and explored its self-powered X-ray detection properties. Where MHy forms the strong hydrogen bond interaction with the inorganic framework, resulting in the asymmetric BiI unit. Meanwhile, the 2 LPEs contribute to generating MHy dipole moments, leading to spontaneous polarization. On the one hand, spontaneous polarization acts as a driving force to realize the X-ray-generated carriers' separation and transport to acquire self-powered detection ability. On the other hand, the reduced noise current and dark current under zero bias further increase the signal-to-noise ratio and lower the detection limit. Notably, the MHyBiI single-crystal-based detector displays a considerable sensitivity (106 μC Gy cm) and an ultralow detection limit (55 nGy s) in self-powered mode. Herein, new insights for constructing polar lead-free perovskite and realizing unprecedented ABiI-type self-powered X-ray detectors are provided.
无铅ABiI型钙钛矿由于其高体电阻率和减少的离子迁移，在直接X射线检测中表现出优异的性能。然而，已报道的中心对称ABiI只能在外部电压下工作，不可避免地导致能量消耗和庞大的单片电路，限制了它们的进一步发展。在此，利用具有2个孤对电子（LPEs）的甲基肼（MHy）阳离子，获得了一种手性极性钙钛矿MHyBiI，并探索了其自供电X射线检测性能。其中，MHy与无机骨架形成强氢键相互作用，导致BiI单元不对称。同时，2个LPEs有助于产生MHy偶极矩，从而导致自发极化。一方面，自发极化作为驱动力，实现X射线产生的载流子的分离和传输，以获得自供电检测能力。另一方面，零偏压下降低的噪声电流和暗电流进一步提高了信噪比并降低了检测限。值得注意的是，基于MHyBiI单晶的探测器在自供电模式下显示出相当高的灵敏度（106 μC Gy cm）和超低检测限（55 nGy s）。在此，为构建极性无铅钙钛矿和实现前所未有的ABiI型自供电X射线探测器提供了新的见解。
