Synthesis And Properties Of Thermally Activated Delayed Fluorescence Acetylenic Polymers Materials

Organic Light Emitting Diodes（OLEDs）have developed rapidly in the past three decades due to their low energy consumption,self-luminescence and flexibility,and have become an indispensable material in the fields of smart displays and lighting.Thermally activated delayed fluorescence（TADF）materials can convert all excitons into photons through the reverse intersystem crossing（RISC）process,achieving a theoretical 100%internal quantum efficiency.TADF materials can perform comparable performance with phosphorescent materials while avoiding the use of heavy metal atoms.Compared with traditional small molecules,TADF polymers possess good solution processability,which can meet the needs of large-scale and low-cost production.Polyalkyne（PA）is a very representative conjugated polymer.The main chains of alternately connected single and double bonds forms aπ-conjugated skeleton,which dispalys special optoelectronic properties.However,due to the exciton trap effect in its conjugated main chain and the defect of photo-generated free radicals,there are few reports of high-efficiency light-emitting molecules based on PA.In Chapter 2,using phenothiazine as the donor and dibenzothiophene sulfone as the acceptor,a TADF monomer molecule with D-A structure was synthesized,and a carbon-carbon triple bond was introduced into the molecule through Sonagashira coupling reaction.A series of PAs with different host/TADF monomer ratios were prepared under rhodium catalysis with the synthesized acetylenic carbazole derivatives host.The copolymers have excellent thermal properties and film-forming properties witn orange-red emission in the thin film states.And the copolymer with a host/TADF monomer ratio of 6:4 can produce delayed fluorescence with aΔE_STof 0.08 e V,which is in line with the design principles of TADF molecules.PA has the potential to generate circularly polarized luminescence（CPL）,and polymers with CPL can be constructed through the strategy of copolymerizing chiral monomers with achiral fluorescent monomers.In Chapter 3,two kinds of PAs with different chiral host/TADF monomer ratios were synthesized by introducing chiral groups into the host molecules under rhodium catalysis.The copolymer with a chiral host/TADF monomer ratio of 7:3 has long-lived fluorescence,and itsΔE_STis calculated to be 0.02 e V,but it does not produce an obvious CD absorption signal.Copolymers with a chiral host/TADF monomer ratio of9:1 can generate CD absorption signals.