Photoluminescence and Scintillation Mechanism of CsPbBr.

Small bandgap scintillators have gained significant attention in recent years. Especially CsPbBr is an interesting material, mitigating the small Stokes shift-related problem of perovskites like CsPbBr. In this work, optical and scintillation properties of CsPbBr single crystals are investigated as a function of temperature, with a detailed focus at 10 K. The CsPbBr single crystals were grown using the vertical Bridgman method. Due to incongruent melting, CsPbBr inclusions are formed, generating a 540 nm emission band. Prepairing CsPbBr via solid-state synthesis yields CsPbBr-inclusion-free material, showing no green 540 nm emission band. In CsPbBr samples with and without CsPbBr inclusions, a new emission band at 610 nm ascribed to an unknown defect was found. Based on the presented experiments, an emission mechanism is proposed for CsPbBr. This shows that both defects and CsPbBr inclusions play a role in the emission behavior of CsPbBr but only the CsPbBr inclusions are responsible for the 540 nm emission.