Molecular engineering of dendritic luminogens with thermally activated delayed fluorescence and aggregation-induced emission characteristics for efficient solution-processed non-doped OLEDs

Endowing thermally activated delayed fluorescence (TADF) emitters with aggregation-induced emission (AIE) characteristics and a fine film-forming ability is significant for realizing efficient solution-processed non-doped organic light-emitting diodes (OLEDs). Herein, a class of AIE-active TADF emitters adopting phenyl ketone as an acceptor and 9,9-diphenyl-9,10-dihydroacridine (or 9,9-dimethyl-9,10-dihydroacridine and phenoxazine) as a donor are exploited. The suppressed intermolecular packing derived from the highly twisted molecular configuration and multiple transition channels induce improved luminescence efficiency and more efficient reverse intersystem crossing (RISC) simultaneously in the solid state. Solution-processed non-doped and doped devices with the maximum external quantum efficiencies (EQEs) of 12.1% and 17.6%, respectively, are obtained when employing the dendritic luminogens of 3PXZ-BPCTPA as the emitter, which are better than the reference non-dendritic luminogens of PXZ-BPCTPA. This work thus provides an approach for designing dendritic luminogens with TADF and AIE features as promising candidates for high-performance solution-processed OLEDs. Improving the luminescence efficiency and reverse intersystem crossing of dendritic luminogens with AIE and TADF features by employing a highly twisted molecular configuration and multiple transition channels for solution-processed OLEDs.