Simple Organic Host/Guest Room Temperature Phosphorescence\nMaterials and Their Application in Security Printing

Recently, the research of organic\nroom temperature phosphorescence\n(RTP) materials has become a research hotspot in the field of materials\nscience and chemistry, especially the use of a small molecule doping\nsystem to achieve long life and efficient RTP. Herein, an efficient\nstimulus responsive room temperature phosphorescent material is prepared\nby a simple host/guest eutectic method. Due to the high crystallinity\nof the host matrix, it provides a rigid environment for the guest\nemitter, and the appropriate triplet energy level provides a bridge\nfor the energy transfer of the guest emitter. The prepared crystal\nmaterial has a long lifetime of RTP with a lifetime of 0.82 s and\na phosphorescence quantum yield of 12.3%. In addition, the introduction\nof fluorescent dyes in the eutectic system can adjust the afterglow\ncolor through energy transfer from triplet to singlet. Interestingly,\nthe RTP properties of this material are sensitive to alkaline environments\nbecause it can destroy the crystalline structure of the host molecule,\nthereby reducing the rigidity of the entire system. Finally, the multicolor\ndisplay and anticounterfeiting encryption of printed patterns are\nsuccessfully applied by using the characteristics of afterglow color\nchange and alkali response of doped materials.