Theoretical investigation of substitution and end-group effects on poly(p-phenylene vinylene)s

Semi-empirical AM1 and ZINDO/S, as well as density function theory (DFT) method B3LYP/6-31G(d) quantum chemical calculations were carried out to study the electronic structures and optical properties of poly(p-phenylene vinylene) derivatives (PPVs) with 10 and 11 phenylene rings in the backbone. The calculations suggest that the assembly of alternate incorporation of CN and alkoxy substituted phenylene rings in the PPV backbone could be a good way to construct organic semiconductors with low HOMO/LUMO energy band-gaps. The effect of the end-group on the electronic structures and optical properties of the conjugated polymer was investigated by the calculated UV-Vis and UPS spectra. It was demonstrated that the aldehyde and phosphate end-groups have limited effects on the photophysical properties in the UV-visible range.