Room temperature phosphorescence (RTP) is a unique photophysical phenomenon. After removing the excitation light source, RTP related materials can emit for several seconds to several hours with a long lifespan. RTP materials have characteristics such as large Stokes shift and long luminescence lifetime, and have application prospects in fields such as information encryption, biological imaging, and chemical sensing. Compared with widely used fluorescent labels, RTP materials have additional time dimensions and richer optical tunability, exhibiting higher concealment and difficulty in replication in multi-level information encoding, making them more suitable for high-level information encryption and anti-counterfeiting. In recent years, the RTP field has developed rapidly, but manipulating RTP performance on demand and efficiently remains a challenge. In addition, further research and optimization are needed on how to integrate multi-color fluorescence and precisely adjustable afterglow for multi-level information encoding to improve encryption security.
In recent years, Chen Tao, a researcher of the Intelligent Polymer Materials Team of the Key Laboratory of Marine Key Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, and Yin Guangqiang, an assistant researcher, have devoted themselves to the controllable construction of composite light-emitting (fluorescent, phosphorescent) materials using supramolecular dynamic interactions and their applications in information storage and encryption, camouflage and anti-counterfeiting.
Recently, the team reported on a strategy for precise control of organic room temperature phosphorescence material properties through lanthanide metal coordination, achieving customized fluorescence and phosphorescence performance, and establishing a high security level of multi-level information encryption and anti-counterfeiting applications. Lanthanide metal ions such as europium and terbium (Ln3+) exhibit forbidden transition processes, which typically require the use of organic ligands with high molar coefficients to sensitize Ln3+for efficient luminescence. This process is called antenna effect. The process of ligand to metal photosensitive energy transfer originates from the triplet state of organic ligands to the high-energy excited state of Ln3+, which competes with the pathway of organic triplet exciton radiation transition to the ground state to form phosphorescence. Therefore, the study integrates Ln3+receptors with long-lived organic phosphorescent donors and introduces this competitive mechanism into long-lived luminescent systems to manipulate RTP performance and achieve customized optical performance. The performance of the lanthanide doped RTP materials obtained by this research institute is highly dependent on the amount of lanthanide metal ions introduced. By adjusting the Ln3+doping amount, specific fluorescence and phosphorescence properties can be obtained as needed. Meanwhile, considering the advantages of precisely customized phosphorescence performance and multi-color tunable fluorescence of the material, the team has established a multi-level information encoding system with high security level, including fluorescence misleading, spatiotemporal resolution anti-counterfeiting, fluorescence phosphorescence dual-mode encrypted lattice, etc. This achievement provides a new approach for precise regulation of organic RTP performance and expands the application of composite optical materials in advanced information security and anti-counterfeiting.
