Effect of Vacancy-Defect on the Electronic and Optical Properties of Cs₃Cu₂I₅ Scintillators: A First-Principles Study

Lead-free copper-based halide perovskite Cs3Cu2I5 crystals have been recognized as a highly promising material in the field of scintillator materials due to their high quantum yield and fast decay characteristics. Their exceptional optical properties and environmental stability render them highly advantageous for gamma and X-ray detection applications, showcasing significant potential for practical use. To conduct a comprehensive analysis of the impact of irradiation defects on the luminescent performance of Cs3Cu2I5 scintillators and their physical mechanisms, this study employs first-principles methods, focusing on the effects of vacancy defects induced by irradiation on the electronic structure and optical properties of Cs3Cu2I5 crystals. The research finds that Cs and Cu vacancy defects introduce shallow energy levels within the material’s bandgap, thereby expanding the luminescent pathways of the crystal and significantly enhancing the radiative recombination rate. In contrast, I vacancy defects create deep energy levels in the bandgap, functioning as nonradiative recombination centers, thereby suppressing luminescent performance. Furthermore, the presence of I vacancy defects exacerbates the self-absorption of visible light in Cs3Cu2I5 scintillators, resulting in a diminished optical signal reaching the photomultiplier tube, and consequently affecting the overall detection efficiency of the scintillator detector. This study reveals the microscopic mechanisms of damage to Cs3Cu2I5 scintillators under high-energy radiation, offering significant theoretical insights for performance optimization and damage protection in practical applications.无铅铜基卤化物钙钛矿（halide perovskite）Cs₃Cu₂I₅晶体被认为是闪烁体材料（scintillator materials）领域极具应用前景的候选材料，其凭借高量子产率（quantum yield）与快速衰减特性获得广泛认可。优异的光学性能与环境稳定性使其在γ射线与X射线探测领域具备显著优势，展现出可观的实际应用潜力。 为全面解析辐照缺陷对Cs₃Cu₂I₅闪烁体发光性能的影响及其物理机制，本研究采用第一性原理方法（first-principles methods），重点探究辐照诱导的空位缺陷对Cs₃Cu₂I₅晶体电子结构与光学性能的调控作用。研究结果表明，Cs与Cu空位缺陷会在材料禁带（bandgap）中引入浅能级，拓宽晶体的发光通道，并显著提升辐射复合（radiative recombination）速率。与之相反，I空位缺陷会在禁带中形成深能级，充当非辐射复合中心（nonradiative recombination centers），进而抑制材料的发光性能。此外，I空位缺陷会加剧Cs₃Cu₂I₅闪烁体的可见光自吸收（self-absorption）效应，导致到达光电倍增管（photomultiplier tube）的光信号强度降低，最终削弱闪烁体探测器的整体探测效率。本研究揭示了高能辐照下Cs₃Cu₂I₅闪烁体的损伤微观机制，可为实际应用中的性能优化与损伤防护提供重要的理论参考。