Single nucleation of Cl-doped FAPbBr₃ with inhibited ion migration for ambipolar radiation detection

Compared with the MAPbBr₃ single crystals (SCs), FAPbBr₃ possesses a better chemical and structural stability and is expected to be a promising organic-inorganic candidate for next-generation room-temperature radiation materials. However, challenges of FAPbBr₃ bulk crystals remain yet, such as numerous nuclei and the intrinsic stability issue, limiting further performance development and large-scale commercialized production. Herein, we report the growth of Cl-doped FAPbBr₃ SCs using an inverse temperature crystallization method and realize single nucleation without a seed. The resulting FAPbBr_2.9Cl_0.1 presents the longest carrier lifetime compared with other components, which reveals the lowest trap-state density. As-grown FAPbBr_2.9Cl_0.1 also exhibits a high resistivity of 4.13 × 10⁹ Ω cm, comparable hole and electron mobility-lifetime products of (1.5-2.1) × 10⁻⁴ cm² V⁻¹, and a high activation energy (E_a) of 0.58 eV, yielding excellent charge transport and collection. Additionally, the AZO/FAPbBr_2.9Cl_0.1/Au device structure markedly reduces leakage current, resulting in a superior I_ON/I_OFF ratio of 22 240 at a bias of 30 V, and distinguishable ²⁴¹Am α-particle pulse height spectra were observed for both electrons and holes with an energy resolution of 19.2% and 21.3%, respectively. These results demonstrate the great potential of FAPbBr_2.9Cl_0.1 SC as a radiation material.