Photoluminescence and Scintillation Mechanism of Cs4PbBr6

Abstract

Small bandgap scintillators have gained significant attention in recent years. Especially Cs₄PbBr₆ is an interesting material, mitigating the small Stokes shift-related problem of perovskites like CsPbBr₃. In this work, optical and scintillation properties of Cs₄PbBr₆ single crystals are investigated as a function of temperature, with a detailed focus at 10 K. The Cs₄PbBr₆ single crystals were grown using the vertical Bridgman method. Due to incongruent melting, CsPbBr₃ inclusions are formed, generating a 540 nm emission band. Prepairing Cs₄PbBr₆ via solid-state synthesis yields CsPbBr₃-inclusion-free material, showing no green 540 nm emission band. In Cs₄PbBr₆ samples with and without CsPbBr₃ 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 Cs₄PbBr₆. This shows that both defects and CsPbBr₃ inclusions play a role in the emission behavior of Cs₄PbBr₆ but only the CsPbBr₃ inclusions are responsible for the 540 nm emission.