Pressure-Driven Color Modulation in Er3+-Doped Cs3Cu2Cl5 Microcrystals

近年来，具有外场响应特性的发光材料因其在压力传感、信息存储、防伪标识以及智能显示等领域展现出重要应用价值而受到广泛关注。金属卤化物材料由于具有柔性的晶格结构、丰富的电子态调控能力以及优异的光学性能，成为压力响应发光研究的重要体系。其中，无铅铜基卤化物Cs3Cu2Cl5因具有较强的自陷激子(self-trapped exciton, STE)发光特性、低毒性以及较好的环境稳定性，被认为是一类具有应用潜力的新型发光材料。然而，目前关于稀土离子调控无铅铜基卤化物发光行为以及外部压力诱导颜色变化机制的研究仍相对有限。本文采用高压原位光致发光测试方法，系统探究了Er3+掺杂Cs3Cu2Cl5在压力作用下的发光颜色调控行为。通过分析不同压力条件下光致发光(photoluminescence, PL)光谱变化，并结合CIE 1931色度坐标对发光颜色进行定量表征，揭示了压力对基质STE发射与Er3+相关发光通道的调控作用。结果表明，在0~14.8 GPa压力范围内，Er3+掺杂Cs3Cu2Cl5表现出明显的压力响应颜色调控特性。常压条件下，样品发光色坐标位于橙黄色区域；随着压力增加至3.1 GPa，基质STE宽带发射峰逐渐减弱，而Er3+相关发射贡献增强，色坐标进入暖白光区域。随着压力继续增加，色坐标逐渐向橙黄色区域移动，最终在14.8 GPa压力下表现出黄色发光。该过程表明，压力能够有效调节Er3+掺杂Cs3Cu2Cl5体系中的发光能级结构及辐射复合过程，实现连续可调的发光颜色变化。本文为无铅卤化物材料在压力传感和可调谐光学器件领域的应用提供理论依据。In recent years, luminescent materials with external field-responsive properties have attracted extensive research attention owing to their promising application prospects in pressure sensing, information storage, anti-counterfeiting labels, smart displays and other fields. Metal halides have emerged as an important research platform for pressure-responsive luminescence by virtue of their flexible lattice frameworks, versatile electronic state tunability and outstanding optical performance. Among them, lead-free copper halide Cs3Cu2Cl5 is regarded as a promising new luminescent material, benefiting from its intense self-trapped exciton (STE) emission, low toxicity and favorable environmental stability. Nevertheless, studies concerning the modulation of luminescence behaviors via rare-earth ions and the mechanism of pressure-triggered color evolution in lead-free copper halides remain relatively scarce. In this work, in-situ high-pressure photoluminescence (PL) measurements were performed to systematically investigate the pressure-dependent color modulation behaviors of Er3+-doped Cs3Cu2Cl5. By analyzing the evolution of PL spectra under various pressures and quantitatively characterizing luminescence color via CIE 1931 chromaticity coordinates, we unraveled the regulatory effect of pressure on the host STE emission and Er3+-associated luminescence channels. The results demonstrate that Er3+-doped Cs3Cu2Cl5 exhibits remarkable pressure-tunable color emission within the pressure range of 0~14.8 GPa. At ambient pressure, the chromaticity coordinate of the sample falls in the orange-yellow region. Upon compression up to 3.1 GPa, the broad-band host STE emission gradually weakens while the contribution of Er3+-related emission rises, shifting the chromaticity coordinate to the warm white light region. Further elevation of pressure drives the chromaticity coordinate back toward the orange-yellow zone, and the material emits yellow light at 14.8 GPa. This evolution verifies that pressure can efficiently modulate the luminescent energy level structure and radiative recombination processes of the Er3+-doped Cs3Cu2Cl5 system, enabling continuous and reversible color tuning. This study provides theoretical guidance for the application of lead-free halides in pressure sensing and tunable optoelectronic devices.