Electronic structure and optical spectroscopy of conducting electrochromicdevices

Interest in conductive organic polymers has considerably increased since th e discovery in 1977 of the doped molecule polyacetylene. Recently, polymers of dithienopyrrole (DP), dithienothiophene (DT) and thionaphtheneindole (T NI) have been synthesized electrochemically showing for several monomer rat ios good electrochromic and conducting characteristics. The aim of this paper is to investigate theoretically the electrical and op tical properties of the above mentioned polymers. Therefore, we have perfor med a conformational structure study followed by electronic structure calcu lations. Also we present a spectroscopic study for oligomers built with the monomers of these materials. In our calculations we utilized the semiempirical method AM1 for the electr onic and geometric simulation of the polymers. Optical absorption spectra f or neutral and charged systems were calculated using the INDO/S-CI method. All three systems showed similar electronic behavior but significant differ ences can be seen on the TNI monomer optical spectra. Our results are in go od agreement with the experimental ones.