Molecular engineering of donor moiety of donor-acceptor structure for management of photophysical properties and device performances

Acridine and carbazole derived electron donors, 8,8-dimethyl-5-phenyl-8,13-dihydro-5H-indolo[2,3-c] acridine (4IA) and 13,13-dimethyl-11-phenyl-11,13-dihydro-5H-indole[2,3-b]acridine(3IA), were synthesized as strong donor moieties of thermally activated delayed fluorescent (TADF) emitters. The new donor moiety was included in the molecular structure of diphenyltriazine based TADF emitter to study the effect of geometrical structure of the donor on the photophysical and device characteristics of TADF emitters. The 4IA donor was better than the 3IA donor for small singlet-triplet energy splitting and TADF emission. TADF behavior was observed only in the 4IA based TADF emitter due to geometrical structure. A TADF emitter having the 4IA based donor moiety exhibited a blue color coordinate of (0.21, 0.31) and a quantum efficiency of 13.7%. (C) 2016 Elsevier Ltd. All rights reserved.