Study On Imide-Based Room-Temperature Phosphorescent Materials

In this dissertation,we have studied the photophysical properties and functionalization of imide-based ultralong room-temperature phosphorescent（RTP）materials and prepared a series of materials with thermally activated delayed fluorescence（TADF）and ultralong RTP properties.In addition,we also synthesized a new type of TADF materials and characterized the photophysical properties of the material and the application of organic light emitting diode（OLED）devices.The details were showed as follows:In the first,three new types of organic light-emitting materials Br-Al-Cz,Cl-Al-Cz and F-AI-Cz were designed and synthesized by changing the halogen substitution groups on phthalimide.They not only showed strong aggregation-induced emission（AIE）effect,but also exhibited thermally activated delayed fluorescence（TADF）in films and crystallization-induced room-temperature phosphorescence（RTP）properties.Especially,RTP with marked afterglow for Br-AI-Cz was observed by naked eye,which could be used as the promising smart materials for the encryption application.In the second,a series of new imide-based luminescent materials o-AI-Cz,m-AI-Cz and p-AI-Cz were prepared by changing the position of the carbazole group.They showed TADF and RTP properties due to their smallΔE_ST in both film and crystalline states.o-AI-Cz exhibited an ultralong RTP with a lifetime of 602 ms in air and remarkable afterglow,which could allow it to be used as a security ink for application in anti-counterfeiting materials.Moreover,o-AI-Cz showed intense intramolecular interaction between the donor and the acceptor subunits,while p-AI-Cz could form regular hexagonal pores with a diameter of13.171?in the solid state,which might result in their different RTP properties.In the third,compound AI-N-Cz was conveniently synthesized,and it exhibited ultralong room-temperature phosphorescence（RTP）with the lifetime of 775 ms,which was more than400 times of the RTP lifetime of its isomer AI-Cz（1.9 ms）.The ultralong RTP of AI-N-Cz might be due to the combination of small singlet-triplet splitting energy(ΔE_ST)and H-aggregation,and it could be an efficient strategy for the further design of ultralong organic room temperature materials.In the fourth,three new emitters,namely Fene,Fens and Yad,featuring quinoline as a new electron acceptor have been designed and conveniently synthesized by changing the type of electron donor.These emitters possessed small singlet-triplet splitting energy(ΔE_ST)and twisted structures,which not only endow them show thermally activated delayed fluorescence（TADF）property but also afford a remarkable aggregation-induced emission（AIE）feature.Moreover,they also showed aggregation-induced delayed fluorescence（AIDF）property and good photoluminescence（PL）property,which are the ideal emitters for non-doped OLEDs.Furthermore,High-performance non-doped organic light-emitting diodes（OLEDs）are achieved with neat film of Fene,Fens and YAD achieved excellent maximum external quantum efficiencies(EQE_max)of 14.9,13.1%and 17.4%,respectively.It was also found that the devices all exhibited relatively low turn-on voltages ranging from 3 V to 3.2 V probably due to their twisted conformation and the AIDF properties.These results demonstrate that the quinoline-based emitters have a promising application in non-doped OLEDs.This dissertation contains 106 Figures,10 Tables,and 147 references.