Hydrochromic materials characterized by noticeable color change upon water exposure have attracted pervasive attention for their frontier applications in sensing and information technologies. However, existing hydrochromic materials typically suffer from a slow hydrochromic response as well as limited stability and color tunability. This work describes a novel hydrochromic perovskite crystal composed of zero-dimensional Cs₃TbF₆:Eu³⁺, which displays switchable luminescence due to the constituent Tb³⁺ and Eu³⁺ ions. Mechanistic investigation reveals that the hydrochromic property stems from a water-induced phase transformation into a one-dimensional structure through a CsF-stripping process. The phase transformation triggers energy coupling between Tb³⁺ and Eu³⁺ ions in adjacent lanthanide halide polyhedra, resulting in an emission color change from green to orange. Notably, the phase transformation is ultrafast (20 ms) and reversible, and the emission color in each phase can be fine-tuned by controlling the Eu³⁺ doping concentration along with Y³⁺ co-doping. The advances in these hydrochromic luminescent materials offer exciting opportunities for information security and data storage.

中文翻译：

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基于镧系元素的水致变色钙钛矿中的超快和多色发光切换

水致变色材料以遇水后颜色发生明显变化为特征，因其在传感和信息技术领域的前沿应用而受到广泛关注。然而，现有的水致变色材料通常具有缓慢的水致变色响应以及有限的稳定性和颜色可调性。这项工作描述了一种由零维 Cs ₃ TbF ₆ :Eu ³⁺组成的新型水致变色钙钛矿晶体，由于成分 Tb ³⁺和 Eu ^{3+而显示出可切换的发光}离子。机理研究表明，水致变色特性源于水诱导的相变，通过 CsF 剥离过程转变为一维结构。相变触发相邻镧系元素卤化物多面体中Tb ³⁺和 Eu ^{3+离子之间的能量耦合，导致发射颜色从绿色变为橙色。值得注意的是，相变超快（20 毫秒）且可逆，并且可以通过控制 Eu 3+}掺杂浓度以及 Y ³⁺共掺杂来微调每个相中的发射颜色。这些水致变色发光材料的进步为信息安全和数据存储提供了令人兴奋的机会。