Density Functional Theory Study of new materials based on thiophene and oxathiazole in their neutral and doped states.

We have investigated the effect of doping in new conjugated compounds based on thiophene and oxathiazole with the dft method at ub3lyp level with 6-31g(d) basis set. our attention focused on the study on the geometries and electronic properties in neutral and doped state. the absorption properties were determined by zindo/s, cis/6-31g(d) and td//b3lyp/6-31g(d) calculations. the effects of doping, the ring structure and the substituent on the geometries and electronic properties of these materials are discussed. we show that the doping process modify both bond lengths and torsion angles and also electronic properties by enhancing the planarity and decreasing the band gap. the results suggest these compounds as good candidates for opto- electronic applications.