Electronic excitations in stacked oligothiophenes

Electronic spectroscopy of oligothiophenes is studied using the semi-empirical ZINDO methodology. Geometry of the neutral, and doubly charged bipolaronic forms of oligomers from 3T to 8T are optimized. Their coordinates are then used to generate various stacked structures up to tetramers. The effects of the length of the chains, number of layers in stacks, stacking distance between chains, deviation from planarity and number and relative positions of bipolaronic forms on the shapes of the electronic excitations are investigated.