Thermally Activated Delayed Fluorescence Conjugated Polymers with Backbone-Donor/Pendant-Acceptor Architecture for Nondoped OLEDs with High External Quantum Efficiency and Low Roll-Off

Most thermally activated delayed fluorescence (TADF) emitters have to be doped in the host for fabricating efficient organic light-emitting diodes (OLEDs) and always suffer from quick efficiency roll-off at high brightness, which severely affect their commercial application in display and lighting fields. In the work, a series of the polymers are synthesized by copolymerization of two carbazole monomers and one acridine derivative monomer containing benzophenone acceptor group. The obtained polymers therefore possess a conjugated backbone with carbazole/acridine moieties and benzophenone pendant to form the twisted donor/acceptor structure. Consequently, the TADF features inherited from the acridine derivative are maintained and improved by managing the content of acridine derivative monomer in the polymers. Solution-processed OLEDs obtained from using neat polymer films exhibit comparable performance with organic TADF small molecules, achieving a maximum external quantum efficiency (EQE) of 18.1% and a very slow roll-off with EQE of 17.8% at the luminance of 1000 cd m(-2).