Suppression of Secondary Phases with Additive Engineering for the Spectrometer-Grade CsPbBr₃ Single Crystals

CsPbBr3 single crystals have garnered significant attention as one of the most promising candidates for room-temperature semiconductor radiation detectors. However, the current solution-based growth of CsPbBr3 single crystals suffers from issues of the formation of secondary phases (CsPb2Br5) and strain-induced cracks in crystals due to high growth temperatures above the phase transition. In this study, 4-bromobutyric acid (BBA) as an additive was introduced in the precursor, which leads to an effective suppression of secondary phase formation and simultaneously a reduction of the crystal growth temperature. The CsPbBr3 single crystals grown with BBA exhibited improved crystal quality, with a full width at half-maximum of (200) X-ray rocking curve (XRC) as low as 0.025° and a high hole mobility-lifetime product (μτh) of 0.57 × 10–4 cm2/V. Moreover, the energy resolution for 57Co γ-ray spectra was improved to around 15.2%, indicating a great improvement in transport properties for CsPbBr3 single crystals grown with BBA. This study suggests that the effective suppression of the CsPb2Br5 secondary phase is likely one of the most important issues for a spectrometer-grade CsPbBr3 detector.