低维钙钛矿Cs₃Cu₂I₅的高压光致发光研究

Study on High-Pressure Photoluminescence of Low-Dimensional Perovskite Cs₃Cu₂I₅

摘要: 低维卤化物钙钛矿Cs₃Cu₂I₅因低毒性、良好的环境稳定性及独特的自陷激子(STEs)宽带发射特性而备受关注。本文采用金刚石对顶砧高压实验装置，结合原位荧光光谱表征技术，研究了Cs₃Cu₂I₅在高压条件下的光致发光行为。研究发现，在0.5 GPa以下，发射曲线呈现不对称形状且向低能区倾斜，这可能是由于压力诱导的晶格畸变促进了STEs的辐射复合；在0.5~5.25 GPa压力范围内，材料出现明显的发射增强，当压力增加到5.25 GPa时，荧光光谱的强度达到峰值。研究结果表明，压力可以有效调控Cs₃Cu₂I₅中[Cu₂I₅]³⁻的畸变程度，进而调制STEs的能量与发射效率。本研究为理解低维无铅钙钛矿在极端条件下的光物理机制提供了参考。

Abstract: Low-dimensional halide perovskite Cs₃Cu₂I₅ has attracted considerable attention due to its low toxicity, good environmental stability, and unique broadband emission characteristics originating from self-trapped excitons (STEs). In this work, the photoluminescence behavior of Cs₃Cu₂I₅ under high pressure was investigated using a diamond anvil cell combined with in situ fluorescence spectroscopy. It is found that below 0.5 GPa, the emission curve exhibits an asymmetric shape and tilts toward the low-energy region, which may be attributed to pressure-induced lattice distortion promoting the radiative recombination of STEs. Within the pressure range of 0.5~5.25 GPa, a significant emission enhancement occurs, and the fluorescence intensity reaches its maximum at 5.25 GPa. The results demonstrate that pressure can effectively modulate the distortion degree of [Cu₂I₅]³⁻ clusters in Cs₃Cu₂I₅, thereby tuning the energy and emission efficiency of STEs. This study provides a reference for understanding the photophysical mechanisms of low-dimensional lead-free perovskites under extreme conditions.