Quantum mechanical investigation of the potential of oligothiophenes and oligoselenophenes as active materials in organic photovoltaic cells

The geometrical, optical and electronic properties of dicyanovinyl substituted oligothiophenes and oligoselenophenes are studied by using Density Functional Theory. The geometry of the oligomers are best predicted using B3LYP, and the absorption properties are calculated using Time-Dependent Density Functional Theory (TD-DFT) methods using M06-2X and ωB97XD functionals. It is found that M06-2X and ωB97XD perform best for predicting absorption properties. The electronic properties are investigated by calculating transfer integrals. The conclusion drawn is that oligoselenophenes are more efficient in charge transfer compared to the oligothiophenes.