Abstract：
The 329-type bismuth (Bi)-based metal halide (MH) polycrystalline films have potential to be applied in the new generation of X-ray imaging technology owing to high X-ray absorption coefficients and excellent detection properties. However, the mutually independent [Bi2X9]3- units and numerous grain boundaries in the material lead to low carrier transport and collection capabilities, severe ion migration, large dark currents, and poor response uniformity. Here, a new multi-phenyl ring methyltriphenylphosphonium (MTP) is designed to optimize the energy band structure. For the first time, the coupling between the A-site cation and [Bi2X9]3- is realized, making it the main contributor to the conduction band minimum (CBM), getting rid of dilemma that carrier transport is confined to [Bi2X9]3-. Further, the preparation of MTP3Bi2I9 amorphous large-area wafer is achieved by melt-quenching; the steric hindrance effect improves stability, increases ion migration energy, and promotes response uniformity (14%). Moreover, the amorphous structure takes advantage of A-site cation participation in the conductivity, achieving a record sensitivity (7601 µC Gy-1 cm-2) and low dark current (≈0.11 nA) in the field of amorphous X-ray detection, and features low-temperature large-area preparation. Ultimately, designing amorphous array imaging devices that exhibit excellent response uniformity and potential imaging capabilities is succeeded here.
摘要：
329型铋（Bi）基金属卤化物（MH）多晶薄膜具有高的X射线吸收系数和出色的检测性能，有望在新一代X射线成像技术中应用。然而,材料中相互独立的[Bi2X9]3-单元和许多晶界导致低载流子传输和收集能力，严重的离子迁移，大的暗电流,响应均匀性差。这里,设计了一种新的多苯环甲基三苯基鳞（MTP），以优化能带结构。第一次,实现了A位阳离子与[Bi2X9]3-之间的耦合，使其成为导带最小值(CBM)的主要贡献者，摆脱承运人运输局限于[Bi2X9]3-的困境。Further,MTP3Bi2I9非晶大面积晶圆的制备是通过熔体淬火实现的；空间位阻效应提高了稳定性，增加离子迁移能量，并促进反应均匀性(14%)。此外，无定形结构利用了A位阳离子在电导率中的参与，在非晶X射线检测领域实现记录灵敏度（7601µCGy-1cm-2）和低暗电流（≈0.11nA），具有低温大面积制备的特点。最终,设计出具有优异的响应均匀性和潜在成像能力的非晶阵列成像器件是成功的。
