Design and Synthesis of a Y-Type Thioxanthone-Carbazole for the Application in Blue and Yellow Organic Light-Emitting Diodes

Abstract

A Y-shaped emitter, TX-Ph2Cz, was designed and synthesized, which uses a thioketone unit as the acceptor and 9,9'-(1,3-phenylene)bis-9H-carbazole as the donor. The compound exhibited blue emission at about 420 nm in diluted solution and a small change in the different solvents with various polarities. In the mixed tetrahydrofuran (THF)/H2O solvents, emission bands had a red shift of 36 nm with the increased content of water. According to the single crystal structure, TX-Ph2Cz showed many intermolecular interaction and the π … π interaction between adjacent molecules would increase the intermolecular charge transfer. Critically, TX-Ph2Cz exhibited blue emission (440 nm) in the doped device, but yellow emission (540 nm) in the non-doped device was originated from the excimer of TX-Ph2Cz. Moreover, the maximum current efficiency and external quantum efficiency of non-doped device were 4.91 cd/A and 2.64%, respectively.