Theoretical study on the electronic structures and photophysical properties of a series of dithienylbenzothiazole derivatives

Exploring the relationship between electronic structure and electroluminescent property has great significance to design some desirable OLED materials. A series of dithienylbenzothiazole derivatives were studied with Density Functional Theory method in this work. The results show that the hole injection/transporting ability of the compound is significantly increased by electron donors (triphenylamine and 9-phenylcarbazole). Introducing the cyano group apparently enhances the electron-injection ability of the compound but reduces its hole-injection ability. The dimethyl-chromene-malononitrile (DCM) group greatly enhances the electron injection/transporting ability of the molecule but has almost no effect on its hole injection/transporting ability. Both the electron reorganization energies and LUMO energy levels of the resulting molecules decrease with increasing electronegativities of the substituents. Extending the π-conjugation length between electron donors and acceptors not only increases the hole/electron injection ability of the molecule, but improves its carrier transport balance.