Theoretical study of the optical,electronic, and charge-transfer properties of 1,2,4,5-tetrakis(phenylethynyl)benzene derivatives for solar cell applications

A series of 1,2,4,5-tetrakis(phenylethynyl)benzene derivatives has been investigated at the CAM-B3LYP/6-31G(d) and TD-CAM-B3LYP/6-31?+?G(d,p) levels to design materials with high performance with respect to suitable frontier molecular orbitals (FMOs), broad absorption spectra, and better and balanced charge-transfer properties. The calculated results reveal that the molecule possessing benzene has the largest torsion angle of these derivatives. Different branches have a slight influence on the distributions of the FMOs of the molecules. 2-vinyl-thieno3,2-b]thiophene branches display a small HOMO–LUMO gap corresponding to red shifts of the absorption spectra. These molecules are potential ambipolar charge-transport materials under the appropriate operating conditions.