Effect Of Molecular Conformation And Enviromental Polarity On Organic Room Temperature Phosphorescence In Crystal

Organic room temperature phosphorescent(RTP)materials have potential applications in bioimaging,LEDs,and data encryption due to their long-life phosphorescence properties.However,factors such as weak spin-orbit coupling,fast non-radiative decays,and multiple quenching effects have blocked the development of RTP.Therefore,the rational design principle to obtain high-performance RTP materials becomes an important issue in the area.Here,in this project,we have designed three molecules with D-A-D structure based on the reported carbazole-dibenzothiophene and carbazole-dibenzofuran systems,and successfully synthesized the compounds and grew single crystals.Through the analysis of properties of single crystals,it was found that the intermolecular interaction,heavy atom effect,molecular conformation and environmental polarity in crystals have great effect on RTP performance.Through the investigation of fluorescence and phosphorescence spectra,it was found that beside intersystem crossing process,the processes of triplet-triplet annihilation and triplet-triplet energy transfer are also found,which have impacts on luminescent properties.Through comparing the structure and photophysical properties of different crystals,unique luminescent material with dual fluorescence and dual phosphorescence is designed by synergistic combination of strong intermolecular interactions,suitable conformation and environmental polarity in crystals.This theis puts forward a new hypothesis,further enriching the design principle of room temperature phosphorescence,and proposing a new idea of constructing high-efficiency luminescence by changing the molecular conformation and introducing the environmental polarity,which provides a new guidline for the design and development of luminescent RTP molecules.