Lead-free ternary copper halides are emerging environmentally friendly materials, which have recently received great attention for their favorable optoelectronic properties. However, few attention was paid to their applications in gas sensing and gas-triggered fluorescence anti-counterfeiting. In this work, we demonstrate an effective Cs₃Cu₂I₅ halide for NH₃ sensing and NH₃-triggered fluorescence anti-counterfeiting applications. The Cs₃Cu₂I₅-based electrical NH₃ sensor exhibits exceptional sensing performance, in which a resistance response of 77.8 % is achieved at 50 ppm NH₃ with a rapid response time (9 s). To elucidate the NH₃ sensing mechanism, we investigated the NH₃-induced optical and structural evolutions including absorption, photoluminescence (PL), and Raman spectra. Our findings suggest that NH₃ molecules, acting as electron donors, adsorb on the Cs₃Cu₂I₅ surface, inducing the decomposition of Cs₃Cu₂I₅ into CsCu₂I₃ and CsI. During this process, the CsCu₂I₃·NH₃ intermediate phase is generated as a shell layer onto the surface of Cs₃Cu₂I₅ grain, leading to an increase in electrical conductivity (or decrease in resistance), and an emission of bright yellow-red fluorescence from CsCu₂I₃. Inspired by NH₃-induced fluorescence emission, we also explored a novel gas-triggered anti-counterfeiting method using Cs₃Cu₂I₅-paper, demonstrating favorable reversibility and convenience, compared to previously reported water-triggered anti-counterfeiting techniques. This work will promote the development of design of Cs₃Cu₂I₅ for gas sensing and gas-triggered fluorescence anti-counterfeiting applications in the future.

中文翻译：

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基于无毒三元卤化铜的 NH3 气体传感和 NH3 诱导防伪


无铅三元铜卤化物是新兴的环保材料，近年来因其良好的光电性能而受到广泛关注。然而，它们在气体传感和气体触发荧光防伪中的应用很少受到关注。在这项工作中，我们展示了一种用于 NH₃ 传感和 NH₃ 触发荧光防伪应用的有效 Cs₃Cu₂I₅ 卤化物。基于 Cs₃Cu₂I₅ 的电气 NH₃ 传感器具有出色的传感性能，在 50 ppm NH₃ 时可实现 77.8% 的电阻响应，响应时间短 （9 s）。为了阐明 NH₃ 传感机制，我们研究了 NH₃ 诱导的光学和结构演变，包括吸收、光致发光 （PL） 和拉曼光谱。我们的研究结果表明，NH₃ 分子作为电子供体，吸附在 Cs₃Cu₂I₅ 表面，诱导 Cs₃Cu₂I₅ 分解成 CsCu₂I₃ 和 CsI。在此过程中，CsCu₂I₃·NH₃ 中间相在 Cs₃Cu₂I₅ 晶粒表面生成壳层，导致电导率增加（或电阻降低），并从 CsCu₂I₃ 发射出明亮的黄红色荧光。 受 NH₃ 诱导荧光发射的启发，我们还探索了一种使用 Cs₃Cu₂I₅ 纸的新型气体触发防伪方法，与以前报道的水触发防伪技术相比，展示了良好的可逆性和便利性。这项工作将促进未来用于气体传感和气体触发荧光防伪应用的 Cs₃Cu₂I₅ 设计的发展。