High efficiency above 20% in polymeric thermally activated delayed fluorescent organic light-emitting diodes by a host embedded backbone structure
A highly efficient polymeric thermally activated delayed fluorescent (TADF) organic light-emitting diode (OLED) was developed by synthesizing a copolymer with 9-vinylcarbazole (VCz) and 10,10′-((6-(4-((4-vinylbenzyl)oxy)phenyl)-1,3,5-triazine-2,4-diyl)bis(4,1-phenylene))bis(9,9-dimethyl-9,10-dihydroacridine) (VTD) repeating units. VCz was introduced as a monomer with a host function and VTD was included as a monomer with an emitter function. The feed ratio of 9-vinylcarbazole and VTD was controlled to study the effect of copolymer composition on the light-emitting performance of TADF OLEDs. It was described that the radical polymerization of the monomer mixture with a feed ratio of the TADF monomer of 10% produced a polymer which achieved a high external quantum efficiency of 22.0%.