Molecular engineering of “A-D-D-A” dual-emitting-cores emitters with thermally activated delayed fluorescence and aggregation-induced emission characteristics

Abstract

Endowing thermally activated delayed fluorescence (TADF) emitter with aggregation-induced emission (AIE) peculiarity is of great significance for realizing more promising commercial applications. Herein, two new dual-emitting-cores emitters with a structure of acceptor-donor-donor-acceptor (A-D-D-A), namely 2DBT-BZ-2Cz and 2DFT-BZ-2Cz, were designed and synthesized to explore their luminescence trait. The emitters, adopting dual carbazole as donor segments and dual phenyl ketone in peripheral skeleton as electron acceptor units, were featured with small singlet (S 1 )–triplet (T 1 ) splitting energy (ΔE ST ) of 0.02 eV and 0.01 eV. The efficient thermally activated delayed fluorescence (TADF) characteristics and aggregation-induced emission property make them suitable for nondoped OLED devices. The solution-processed green OLEDs based on 2DBT-BZ-2Cz demonstrated greater device performance with current efficiency of 20.7 cd A −1 and maximum luminescence of 10,000 cd m −2 . This work thus provides the direction to explore luminogens of dual-emitting-cores with TADF and AIE features as promising candidates in solid state lighting. Two novel AIE-active TADF materials with dual-emitting cores, namely 2DBT-BZ-2Cz and 2DFT-BZ-2Cz, were designed and synthesized, in which efficient separation of frontier molecular orbital (FMO) and highly twisted molecular structure induced similarly small ΔE ST , obvious TADF characteristic and AIE feature. • Two TADF emitters with dual emitting cores are constructed with the similar molecular configuration of A-D-D-A. • Efficient separation of frontier molecular orbital induced similarly narrow ΔE ST and distinct TADF characteristic. • Highly twisted molecular structure of the dual emitting cores restricted the π-π packing and abduct AIE feature.