Time-temperature indicator(TTI)technologies enable real-time quality monitoring of perishable products during transportation-storage.Photochromic material-guided TTI offers significant benefits in terms of nondestructive and convenient visualization.However,photochromic materials with low-temperature-range dependency are rare,limiting the development of cryogenic temperature-responsive TTI methods.This work proposes a novel temperature-gated bicolor photochromic material.Using NaYTiO_(4)as the matrix,which has a native blue color center related to the intrinsic deep trap,Bi^(3+)ions are incorporated to create extremely shallow trap levels(100-230 K)along with an associated longwavelength absorption color center.By combining these two color centers with extended full-spectrum absorption,NaYTiO_(4):Bi^(3+)converts to dark gray upon ultraviolet irradiation below 233 K.With increasing temperature,the trapped electrons in shallow traps are released first,and the color state becomes yellowish until it completely fades back to white above 573 K.The liberation of thermally activated charge carriers is positively correlated with the storage duration and the ambient temperature.For the first time,we realize a TTI method based on photochromic materials at extremely low temperatures,which allows for direct visualization of quality management for cryogenic products without further information extraction and conversion.This work demonstrates the significant ability of photochromic materials as advanced information-recording materials in the next generation of smart TTIs.
Yunwen BaoWei HuYiqing ZhouZhongxian QiuJingxuan ZhangJiaping ZhangJiaren DuShixun Lian
易腐产品由于其温度敏感特性,环境温度异常波动容易导致其在生产、流通、储存以及销售等环节的品质劣变。这不仅会造成资源浪费,经济损失、环境污染,还会对公众健康构成严重威胁。因此,发展能够实时监测产品品质的技术和设备具有十分重要经济和社会价值。时间-温度指示器(Time temperature indicator,TTI)能够同时记录易腐产品所经历的时间和温度信息,从而实现实时、无损的产品品质预测。近年来,关于TTI的研究日益受到相关领域科研工作者的日益重视。为了加快本领域的发展,本文对不同类型TTI的工作原理、应用实例、优缺点做了简要总结,同时介绍了共价有机框架材料型TTI的最新研究进展,讨论了TTI面临的挑战的发展及其发展趋势。
