Fast solution-phase growth of centimeter-sized Cs₃Cu₂X₅ (X = Cl, I) single crystals for high-performance scintillators

Fast and convenient synthesis of zero-dimensional (0D) cesium-copper(I) halide (Cs₃Cu₂X₅ (X = Cl, I)) single crystals (SCs) is critical to achieve practical radiography. In this study, rapid growth of high-quality Cs₃Cu₂X₅ (X = Cl, I) SCs with sizes reaching centimeter scale were achieved within 24 hours using scalable solution-phased methods. These crystals exhibited highly effective emission with large Stokes shifts, excellent PL linearity, and PLQYs exceeding 86%. Additionally, post-treated Cs₃Cu₂X₅–PMMA films demonstrated outstanding scintillation performance, including excellent stabilities, light yield surpassing 36 000 photons per MeV, and spatial resolution up to 6.5 lp per mm in X-ray imaging tests. The high scintillation efficiency can be attributed to their compact 0D crystalline structure, resulting in a small defect density and strong exciton localization.