On May 5th, the research group of Associate Professor Yang from School of Materials, Chongqing University of Technology published an article entitled "Ultra-long Room Temperature Phosphorescence from Amorphous Organic Materials to Confid" in the sub-issue of top international publications. Ential information encryption and decryption, which is the first report in the world on amorphous polymer-based long-lasting luminescent materials and their applications in the field of encryption and decryption of confidential information. School of Materials, Chongqing University of Technology is the first unit of the paper, and the graduate students of the School of Materials are the first author. Associate Professor Yang and the partner professor of Nanyang Technological University are the corresponding authors of the paper.

This paper was selected as the highlight of scientific progress and reported on the official website. This is the first time that the scientific research achievements of colleges and universities in Chongqing have been published in the first edition of Science, and have been reported in a rolling way.

Long afterglow luminescence is a unique photophysical phenomenon, which can last for a period of time after the excitation light source is removed. This phenomenon generally exists in inorganic materials, such as the night pearl. Compared with inorganic long-afterglow materials, organic long-afterglow luminescent materials have the advantages of good biocompatibility, good flexibility and easy modification of functional groups, and have great application prospects in many high-tech fields such as biological imaging, optical recording, information storage and anti-counterfeiting systems. However, the phenomenon of pure organic long afterglow can only be observed under harsh conditions such as extremely low temperature (77 K) and oxygen-free environment, so it is a great challenge to realize efficient organic long afterglow at room temperature.

Based on this, the research group of Associate Professor Yang cooperated with the research group of Nanyang Technological University to independently design a hexa (4- carboxylic acid-phenoxy)-cyclophosphazene (G) guest molecule with six benzoic acid units (Figure 3). At room temperature, G itself does not emit any fluorescence or phosphorescence. When G is introduced into PVA matrix film, after the excitation light source is turned off, it shows obvious long afterglow phenomenon and shows strong dependence on ultraviolet radiation (Figure 3). Based on the radiation dependence, the research team innovatively developed a green ink-free screen printing technology with independent knowledge production field, which can be applied to advanced anti-counterfeiting of bills, luxury goods, banknotes, military/government confidential documents and so on. (Figure 4).

The research work has been strongly supported by the National Natural Science Foundation of China, the National Study Abroad Fund, the Chongqing Municipal Science and Technology Commission, the Chongqing Municipal Education Commission, the Singapore Academic Research Fund, and the first scientific research teams of the Institute of Materials and Polymer Materials and Processing Technology.

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