Er³⁺掺杂Cs₃Cu₂Cl₅的高压荧光光谱研究

High-Pressure Photoluminescence Study of Er³⁺-Doped Cs₃Cu₂Cl₅

摘要: 压致变色材料作为一种能够响应外界压力并改变其发光颜色的智能材料，在压力传感、信息加密和防伪识别等领域展现出巨大的应用潜力。铜基卤化物钙钛矿(如Cs₃Cu₂X₅，X = Cl, Br, I)具有无毒、窄带宽发光、价带由Cu-3d轨道主导导致的强局域激子效应，在小压力下即可产生明显的发光变化，适用于可逆、多级分辨的压致变色响应。稀土离子掺杂是提升钙钛矿材料性能的核心改性手段。然而，对于稀土离子掺杂与Cu(I)基钙钛矿之间的协同效应尚缺乏系统研究。本文以掺铒离子的Cs₃Cu₂Cl₅微晶材料(Cs₃Cu₂Cl₅: 50% Er³⁺)为研究对象，结合金刚石对顶砧原位高压荧光光谱技术，探究其在9 GPa下的光致发光演化规律。结果表明，Cs₃Cu₂Cl₅：50% Er³⁺的光学行为呈两阶段演化特征，在0∼3 GPa压力范围内荧光峰强度逐渐减弱，3∼9 GPa范围内荧光峰强度反而增强。本文揭示了Cs₃Cu₂Cl₅：50% Er³⁺在高压下的多中心发光竞争机制，证实了稀土离子局域化4f-4f跃迁的本征压力稳定性，为稀土掺杂卤化钙钛矿的高压研究和新型发光器件的设计提供了理论依据。

Abstract: Piezoluminescent materials, as a class of smart materials capable of responding to external pressure and changing their emission color, exhibit significant application potential in pressure sensing, information encryption, and anti-counterfeiting identification. Copper-based halide perovskites (such as Cs₃Cu₂X₅, X = Cl, Br, I) possess advantages including non-toxicity, narrow-band emission, and strong localized excitonic effects arising from valence bands dominated by Cu-3d orbitals, enabling noticeable luminescence variations even under low pressure and making them suitable for reversible and multi-level pressure-responsive chromic behavior. Rare-earth ion doping is a key modification strategy for enhancing the performance of perovskite materials. However, systematic investigations on the synergistic effects between rare-earth ion doping and Cu(I)-based perovskites remain limited. In this work, erbium-ion-doped Cs₃Cu₂Cl₅ microcrystals (Cs₃Cu₂Cl₅: 50% Er³⁺) were selected as the research system, and their pressure-dependent photoluminescence evolution up to 9 GPa was investigated through in-situ high-pressure fluorescence spectroscopy using a diamond anvil cell. The results demonstrate that Cs₃Cu₂Cl₅: 50% Er³⁺ exhibits a two-stage evolution in optical behavior, where the fluorescence intensity gradually decreases within the pressure range of 0~3 GPa and subsequently increases within the range of 3~9 GPa. This study reveals the competitive multi-center luminescence mechanism of Cs₃Cu₂Cl₅:50%Er³⁺ under high pressure and confirms the intrinsic pressure stability of localized 4f-4f transitions of rare-earth ions. These findings provide a theoretical basis for high-pressure investigations of rare-earth-doped halide perovskites and for the design of novel luminescent devices.