Sm2+-doped CsEuI3 crystals with highly efficient near-infrared emission and X-ray radioluminescence

Abstract

Near-infrared (NIR)-emitting scintillators coupled with high-quantum-efficiency silicon-based photodetectors are an effective strategy to improve the radiation detection properties. In this study, the highly efficient broad NIR-emitting CsEuI₃ halide scintillator is developed via Sm²⁺ doping. The centimeter-scale CsEuI₃:Sm²⁺ scintillation crystals were successfully grown using the Bridgman method. The crystal structure and composition were analyzed and discussed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS), revealing that Sm²⁺ successfully replaces Eu²⁺ in the crystal lattice. Under ultraviolet (UV) and X-ray excitation, the broad 5d - 4f emission band of Sm²⁺ and Eu²⁺ are observed, peaking at 825 and 452 nm, respectively. The CsEuI₃:Sm crystal presents a high NIR photoluminescence quantum yield (PLQY) of 80.5 %. The energy transfer processes between Eu²⁺ and Sm²⁺ are investigated by using photoluminescence (PL) spectra and decay kinetics. The scintillation mechanism, luminescence thermal stability and defect are discussed based on thermoluminescence (TL) and variable-temperature X-ray luminescence (XEL). This work provides a novel NIR scintillation material with excellent performance for applications in radiation detection, NIR spectroscopy and night vision.