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