Solution-Grown Formamidinium Hybrid Perovskite (FAPbBr₃) Single Crystals for α-Particle and γ-Ray Detection at Room...

Compared with the widely reported MAPbBr₃ single crystals, formamidinium-based (FA-based) hybrid perovskites FAPbBr₃ (FPB) with superior chemical and structure stability are expected to be more efficient and perform as more reliable radiation detectors at room temperature. Here, we employ an improved inverse temperature crystallization method to grow FPB bulk single crystals, where issues associated with the retrograde solubility behavior are resolved. A crystal growth phase diagram has been proposed, and accordingly, growth parameters are optimized to avoid the formation of NH₄Pb₂Br₅ secondary phase. The resulting FPB crystals exhibit a high resistivity of 2.8 × 10⁹ Ω·cm and high electron and hole mobility-lifetime products (μτ) of 8.0 × 10^-4 and 1.1 × 10^-3 cm²·V^-1, respectively. Simultaneously, the electron and hole mobilities (μ) are evaluated to be 22.2 and 66.1 cm²·V^-1·s^-1, respectively, based on the time-of-flight technique. Furthermore, a Au/FPB SC/Au detector is constructed that demonstrates a resolvable gamma peak from 59.5 keV ²⁴¹Am γ-rays at room temperature for the first time. An energy resolution of 40.1% is obtained at 30 V by collecting the hole signals. These results demonstrate the great potential of FAPbBr₃ as a hybrid material for γ-ray spectroscopy and imaging.