Formamidinium (FA)-based hybrid lead halide perovskites (FAPbX₃, X=I or Br/I) have recently led to significant improvements in the performance of perovskite photovoltaics. The remaining major pitfall is the instability of α-FAPbI₃, causing the phase transition from the desired three-dimensional cubic perovskite phase to a non-perovskite one-dimensional hexagonal lattice. In this work, we report the facile, inexpensive, solution-phase growth of cm-scale single crystals (SCs) of variable composition Cs_xFA_1−xPbI_3−yBr_y (x=0–0.1, y=0–0.6) which exhibit improved phase stability compared to the parent α-FAPbI₃ compound. These SCs possess outstanding electronic quality, manifested by a high-carrier mobility–lifetime product of up to 1.2 × 10⁻¹ cm² V⁻¹ and a low dark carrier density that, combined with the high absorptivity of high-energy photons by Pb and I, allows the sensitive detection of gamma radiation. With stable operation up to 30 V, these novel SCs have been used in a prototype of a gamma-counting dosimeter.

基于甲（FA）的混合卤化铅钙钛矿（FAPbX ₃，X = I或Br / I）最近已导致钙钛矿光伏电池性能的显着提高。剩余的主要缺陷是α-FAPbI的不稳定₃，导致从期望的三维立方钙钛矿相到非钙钛矿一维六边形格子的相变。在这项工作中，我们报告了组成可变的Cs _x FA _{1− x} PbI _{3− y} Br _y（x = 0–0.1，y = 0– 0.6）相较于母体α-FAPbI具有更好的相稳定性_3个化合物。这些超导体具有出色的电子质量，其表现为高载流子迁移率–寿命积高达1.2×10 ^-1 cm ²  V ^-1，暗载流子密度低，再加上Pb对高能光子的高吸收性和I，允许灵敏地检测伽玛射线。这些新型SC具有高达30 V的稳定工作电压，已被用于伽玛计数剂量计的原型中。