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 (μτ_h) 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.