Synthesis And Optical Properties Study Of Pure Organic Room Temperature Phosphorescent Materials With Long Lifetime And Bright Long-lasting Afterglow

Pure organic room temperature phosphorescence(PORTP)materials have significant applications in the fields of information storage,biological imaging,anti-counterfeiting and encryption,and sensing,etc.,because of their advantages of low toxicity,low cost,good biocompatibility,appreciable stability,and good processability,etc.,as well as their unique photochemical properties.However,PORTP materials are difficult to exhibit strong phosphorescence emission at room temperature because of weak spin-orbit coupling.In this paper,combined with phosphorescent emission mechanism,we designed and synthesized a series of compounds with commercial carbazole as donor,benzene and pyridine as receptor,and introduced polar groups cyano(-CN)and amide(-CONH₂),then obtained room temperature phosphorescent(RTP)materials with long lifetime,bright long-lasting afterglow properties.The commercial carbazole as the constructing unit of room temperature phosphorescence materials.First,we designed and synthesized Cyanocarbazole derivatives,which showed the RTP lifetimes of 400 ms and afterglow of more than 4 s in the dark environment.For the amide carbazole derivatives,the RTP properties of the compounds were significantly enhanced,the ultralong lifetime of 900ms and the afterglow of more than 6s.Different polar groups have different effects on the RTP properties,which has certain significance for the construction of excellent RTP materials.By controlling the crystallization conditions to achieve the polycrystalline system of a biscarbazole-based molecule,the two crystal structures have different phosphorescence properties,but both have RTP characteristics of ultralong lifetime(more than 900ms)and long afterglow.In particular,one of the crystal structures emits persistent white afterglow,and it still exhibits stable white afterglow emission at different excitation wavelengths,it has been proved that the white light emission is produced by the complementation of the long-lived delayed fluorescence and the triplet phosphorescent emission.Through the single crystal analysis of these compounds,analyze the effects of molecular structure and intermolecular packing mode on the lifetime and afterglow properties of room temperature phosphorescent materials,which provide a certain theoretical basis for the design and develop the room temperature phosphorescent materials with long lifetime and bright long-lasting afterglow properties.