Efficient Deep Blue Luminescent Materials With Hybrid Local and Charge Transfer Characteristics for High‐Performance OLEDs

ABSTRACT Robust blue emitters are highly demanded for the industry of organic light‐emitting diodes (OLEDs), but still remain challenging. Herein, two tailored deep blue compounds (2PCzTRZ‐tCz and 2DBFTRZ‐tCz) with the dendritic donor–acceptor structure consisting of a weak electron acceptor of 9‐phenylcarbazole or dibenzofuran substituted triazine and a weak electron donor of 3,6‐di‐ tert ‐butyl‐9‐methyl‐9 H ‐carbazole are developed. These two compounds enjoy excellent thermal stability and exhibit deep blue photoluminescence (PL) both in toluene solutions (425 and 438 nm) and doped films (449 and 457 nm) with high quantum yields. They hold a hybridized local and charge‐transfer (HLCT) nature and prefer horizontal dipole orientation. They display efficiently deep blue electroluminescence (EL), furnishing high maximum external quantum efficiencies (EQE _max s) of 7.6 and 5.9% with EL peaks at 432 and 440 nm and CIE _x,y coordinates of (0.156, 0.067) and (0.151, 0.070) in non‐doped devices, and even better EQE _max s of 10.6% and 11.7% with EL peaks at 442 and 450 nm and CIE _x,y coordinates of (0.154, 0.107) and (0.146, 0.104). These findings provide valuable guidance for the development of efficient blue luminescent materials for OLEDs.