A directly coupled dual emitting core based molecular design of thermally activated delayed fluorescent emitters

Abstract

New green thermally activated delayed fluorescence (TADF) materials built on a directly coupled dual emitting core based backbone structure were designed, synthesized, and applied as green dopants in TADF devices. An ortho-linkage between a carbazole or 3,6-di-tert-butylcarbazole donor and a triazine acceptor facilitated the TADF emission, and direct coupling of the two TADF emitting cores more than doubled the external quantum efficiency of the TADF devices. The TADF emitter based on the directly coupled dual emitting core design exhibited a green emission with a CIE coordinate of (0.23, 0.52) and a maximum external quantum efficiency of 20.8% compared with less than 10% efficiency of a conventional TADF emitter with the corresponding chemical structure.