Room temperature phosphorescence based on nitrogen-phosphorus co-doped carbonized polymer dots for information encryption

Carbonized polymer dots (CPDs) are proposed as a novel room temperature phosphorescence (RTP) materials that widely used in optoelectronic devices, bioimaging, especially in the field of information encryption and anti-counterfeiting due to their unique optical properties. However, achieving RTP emission under matrix-free conditions requires reasonable structural design to prevent the quenching of triplet excitons, which is very challenging. Herein, we proposed a facile, rapid and effective strategy to prepare matrix-free nitrogen and phosphorus co-doped CPDs (named Arg-CPDs) via microwave assisted heating treatment of arginine (Arg) and phosphoric acid. The Arg-CPDs exhibit bright blue fluorescence in aqueous solution and yellow green RTP emission in solid state, and the RTP emission is visible to the naked eye for about 4 s after switching-off the UV lamp. The phosphorescence lifetime of Arg-CPDs was 149 ms and 667 ms in ambient conditions and low temperature (77 K), respectively, which shown that the typical phosphorescent properties. Moreover, potential applications of the Arg-CPDs in the fields of information protection and encryption are demonstrated. This study provides a facile strategy for the preparation of matrix-free CPDs-based RTP materials toward the information security and their successful application in information security.