Highly efficient nondoped blue organic light-emitting diodes based on a star-group tetraphenylethylene-substituted aggregation-induced-emission-active organic fluorescent small molecules

Abstract

Tetraphenylethene (TPE) is a star group exhibiting an excellent aggregation-induced emission (AIE) effect. Although significant progress has been made in the field of organic electroluminescence (EL) based on TPE-substituted emitters, highly efficient and high-color-purity TPE-substituted blue fluorophores with the AIE effect are still very rare. In this paper, a simple and effective molecule—N-phenyl-N-(4-(1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl)phenyl)-4′-(1,2,2-triphenylvinyl)-[1,1′-biphenyl]-4-amine (TPETPAPI)—was designed and synthesized using triphenylamine (donor), phenanthroimidazole (acceptor), and tetraphenylethylene (AIE generator). In tetrahydrofuran solution, the molecule emits little light and the quantum efficiency is low (1.3%); however, the fluorescence is enhanced in the film (73%), exhibiting remarkable AIE properties, thus enabling TPETPAPI to be used in future applications in organic light-emitting diodes. The nondoped device exhibits a low turn-on voltage of 3.0 V, a maximum luminance of 10780 cd m−2, maximum current efficiency of 12.20 cd A−1, and maximum power efficiency of 11.95 lm W−1, with an EL peak at 476 nm. TPETPAPI exhibits the most impressive EL performance reported to date for a TPE-substituted blue fluorophore with AIE' characteristics.