High Yield Solution Growth of FACsPbBr3 Single Crystals with Low Defect Density for Gamma-ray Spectroscopy

Abstract Metal halide perovskites are promising candidates for room temperature gamma-ray spectrum detectors, however, it is challenging to grow high-quality single crystals under operation conditions to make them economically competitive to existing materials. Here, we report the growth of centimeter-size formamidinium-cesium lead bromide (FACsPbBr 3 ) single crystals at high yield from low purity (98%) and thus low-cost precursors using a relatively low-temperature solution method. The introduction of FA into CsPbBr 3 reduces defect density in crystals by eliminating the phase transition during the cooling from the growth temperature to room temperature, which significantly improves the yield of crack-free and low trap density crystals. As-grown FACsPbBr 3 exhibits a high resistivity of 9.5×10 9 Ω cm, balanced hole and electron mobility-lifetime products of (2.2–3.2) ×10 − 3 cm 2 V − 1 , a long charge recombination lifetime of 182 ns, and a record low deep trap density of 5.6 × 10 10 cm − 3 , which eventually results in a high charge collection efficiency of 84% under gamma-ray. The FACsPbBr 3 spectrum detectors with an asymmetrical metal electrode configuration have achieved an energy resolution of 2.9% for 662 keV 137 Cs γ-rays. The improved spectrum capability allows them to resolve Pb K α,β X-rays (75–85 keV) for the first time in 137 Cs spectrum. FACsPbBr 3 single crystals show excellent stability under large biases up to 1000 volts, and no degradation of spectrum performance after 7 months.