CsCu₂I₃闪烁体空位缺陷光电性质的第一性原理研究

First-Principles Study on the Optoelectronic Properties of Vacancy Defects in CsCu₂I₃ Scintillators

摘要: 无铅铜基卤化物钙钛矿CsCu₂I₃晶体，以其高量子产率和快速衰变特性，在闪烁体材料领域崭露头角。其更快的光衰变和单向高效的电荷载流子传输，使其在X射线探测成像领域备受青睐，展现出巨大的应用潜力。为了揭示辐照缺陷对CsCu₂I₃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，重点计算了辐照引发的空位缺陷对CsCu₂I₃晶体电子结构和光学性质的影响。研究发现，Cs和Cu空位缺陷会在材料带隙中引入浅层能级，这不仅拓展了晶体的发光路径，还提高了辐射复合速率；而I空位缺陷则在带隙中形成深层能级，充当非辐射复合中心，从而抑制发光性能。此外，I空位缺陷的存在还增强了CsCu₂I₃闪烁体对可见光的自吸收能力，导致传入光电倍增管的光信号减弱，进而影响闪烁体探测器的探测效率。本研究揭示了CsCu₂I₃闪烁体在高能射线辐照下损伤的微观机理，为其在实际应用中的性能优化和损伤防护提供了重要的理论依据。

Abstract: Lead-free copper-based halide perovskite CsCu₂I₃ crystals have emerged in the field of scintillator materials due to their high quantum yield and fast decay characteristics. Their faster luminescence decay and unidirectional efficient charge carrier transport make them highly favored in the field of X-ray detection and imaging, showing great application potential. To reveal the impact of irradiation defects on the luminescence properties of CsCu₂I₃ scintillators and the underlying physical mechanisms, this study employs first-principles methods to focus on calculating the effects of irradiation-induced vacancy defects on the electronic structure and optical properties of CsCu₂I₃ crystals. The findings indicate that Cs and Cu vacancy defects introduce shallow levels into the band gap of the material, which not only expands the luminescence pathways of the crystal but also significantly increases the radiative recombination rate. In contrast, I vacancy defects form deep levels in the band gap, acting as non-radiative recombination centers and thus suppressing luminescence performance. Moreover, the presence of I vacancy defects also enhances the self-absorption of visible light in CsCu₂I₃ scintillators, weakening the light signals entering the photomultiplier tube and thereby affecting the detection efficiency of scintillator detectors. This study reveals the microscopic mechanisms of damage in CsCu₂I₃ scintillators under high-energy radiation, providing important theoretical basis for the performance optimization and damage protection of CsCu₂I₃ scintillators in practical applications.