Hydrochromic materials undergo magical color changes when interacting with water and are receiving widespread attention for their frontier applications such as sensing and information security. The hydrochromic effect is observable in perovskite materials via the mechanism of water-induced fluorescence quenching. However, due to water isolation, achieving a hydrochromic effect in perovskite-polymer composite remains elusive, notwithstanding its importance as a potentially commercial-ready material. Here, we demonstrate a hydrochromic effect of perovskite-polymer-based porous composite via a nonsolvent-induced phase separation method, comprising of FA₂PbBr₄/poly(vinylidene fluoride) (FA = formamidinium). The naturally formed pores serve as microchannels, facilitating moisture diffusion. The penetrated water induces a phase transition of perovskite material from the nonfluorescent two-dimensional FA₂PbBr₄ to the fluorescent three-dimensional FAPbBr₃. This work has developed the hydrochromic perovskite-polymer composites, enabling various commercial-ready chromatic applications as conceptually demonstrated custom-made fingerprint labels, quick response code anticounterfeiting labels, encrypted document protections, and water-ink inkjet printing.

中文翻译：

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钙钛矿-聚合物复合材料的氢变色效应


氢变色材料在与水相互作用时会发生神奇的颜色变化，并因其传感和信息安全等前沿应用而受到广泛关注。通过水诱导荧光猝灭的机制，可以在钙钛矿材料中观察到水变色效应。然而，由于水的隔离，尽管钙钛矿-聚合物复合材料作为一种潜在的商业就绪材料很重要，但在钙钛矿-聚合物复合材料中实现氢变色效应仍然难以捉摸。在这里，我们通过非溶剂诱导的相分离方法展示了钙钛矿-聚合物基多孔复合材料的水变色效应，该方法由 FA₂PbBr₄/聚（偏二氟乙烯）（FA = 甲酰胺）组成。自然形成的孔隙充当微通道，促进水分扩散。渗透的水诱导钙钛矿材料从非荧光二维 FA₂PbBr₄ 到荧光三维 FAPbBr₃ 的相变。这项工作开发了氢变色钙钛矿-聚合物复合材料，实现了各种商业就绪的彩色应用，如概念演示的定制指纹标签、快速响应代码防伪标签、加密文件保护和水性喷墨打印。