Synthesis, crystal structure, aggregation-induced emission enhancement and electroluminescence properties of a novel compound containing carbazole and triarylborane groups

Abstract

A novel compound 9,9′- (4′ - (dimesitylboranyl) - [1,1′ - biphenyl] - 3,5 - diyl)bis(9H - carbazole) (DB-BCZ) was synthesized by using carbazole as electron-donors and triarylborane as an electron-acceptor. Its structure was adequately characterized by elemental analysis, mass spectrometry, NMR spectroscopy and X-ray crystallography.The thermal stability, photophysical properties and electrochemical properties of DB-BCZ were systematically investigated. The results show that DB-BCZ possesses good thermal stability with Td of 394 °C and aggregation-induced emission enhancement (AIEE) feature. The single structure of the crystal presents a twisted propeller configuration, belonging to monoclinic system with space group symbol Cc. The packing structure of the crystal shows that there are hydrogen bonds (C-H⋯π and C-H⋯H) formed between adjacent molecules, and there is no typical π-π interaction between the aromatic rings, which may be the main reason for the formation of AIEE. Furthermore, non-doped OLED employing DB-BCZ as emitting layer displays bluish-violet emission, and exhibits a turn-on voltage of 5.6 V, a maximum luminance of 5374 cd m−2, a maximum current efficiency of 2.26 cd A−1 and a maximum power efficiency of 0.96 lm W−1. Meanwhile, the device is slow in efficiency roll-off. The results demonstrate that DB-BCZ is a promising candidate for OLEDs.