Design and synthesis of D-A-D′ type compounds with AIE characteristics for hybrid WOLED with stable chromaticity

Abstract

A series of donor–acceptor–donor’ (D-A-D′) type compounds with aggregation-induced emission (AIE) were designed and synthesized by using imidazole as an acceptor and triphenylamine and indolocarbazole as different donors. The non-coplanar structure could effectively eliminate the molecular aggregation-caused quenching (ACQ). Meanwhile, the electron push-pull character could be adjusted by introducing different substituents to achieve the high-efficiency fluorescence from its locally excited (LE) state. The electronic structures, electrochemical behavior, thermal stability, photophysical properties and electroluminescence (EL) performance of these compounds were systematically studied. Four new materials were evaluated as the blue emitters in non-doped OLEDs, and all devices present stable blue emissions with premium EL performance. Furthermore, a hybrid white organic light-emitting diode (WOLED) was prepared by using the compound 5b as the double blue emitting layer and the compound 5d as the host doping with phosphorescent dye. The maximum current efficiency and external quantum efficiency of the device were 67.6 cd/A and 24.3%, respectively. Especially, the WOLED showed ultra-stable CIE coordinates of (x = 0.337 ± 0.003, y = 0.341 ± 0.002) as the driving voltage increases from 5 V to 12 V. This work provides an idea for the design of AIE molecules and a practical strategy to achieve multifunctional light-emitting devices.