Star-shaped thermally activated delayed fluorescence emitters with a tri-armed arylsulfonic acceptor for efficient solution processed organic light emitting diodes†
A tri-armed arylsulfone-based acceptor (SF) linked by triphenylbenzene (TPB) has been developed to construct solution-processable thermally activated delayed fluorescence (TADF) materials with large band gaps. The acceptor suffered limited conjugation due to the tetrahedral geometry of sulfonyl groups, as well as a meta-linkage at the central TPB moiety. By simple conjugation of the SF with appropriate donor units, luminophores SF–DMAC and SF–PXZ capable of producing efficient blue/green emissions were obtained, with peak efficiencies of 11.3% (19.0 cd A−1 and 10.0 lm W−1) and 12.4% (35.6 cd A−1 and 17.8 lm W−1) in the corresponding wet-processed OLEDs. Decent resistance to roll-off at high brightness was noticed in the device based on SF–PXZ, ascribing to reduced intermolecular interactions due to its star-shaped architecture and an efficient reverse intersystem crossing (RISC) process.