A DENSITY FUNCTIONAL THEORY STUDY OF SUBSTITUTED AND BRIDGED OLIGOTHIOPHENES FOR ELECTROCHEMICAL APPLICATIONS

Abstract

In this work the electronic and thermodynamic properties of both neutral and radical cationic oligothiophene chains with up to eight thiophene units, substituted and bridged oligothiophenes are investigated by performing hybrid DFT (BH and HLYP) and Hartree-Fock calculations using 6-31G* and 6-311G** basis sets. The thermodynamic property calculations show the radical cationic species are less stable than the corresponding neutral species. Oxidizing the oligomers decreases their band gap. The results obtained show that introducing side attachments like alkoxy and cyano substituents at 3-position lowers the band gap of the oligomers. Modifying the oligothiophene backbone by introducing bridge between two thiophene units also enhances the stability and lowers the band gap of the oligomers.