Spectroscopic study of polyazopyrroles (a narrow band gap system)

Polyazopyrroles are systems that are derived from the dipyrroles by inserting an azo group among the pyrroles rings. This new polymer present a significant decrease in energy gap lowering from 2.5 eV to 1.0 eV. In this work we present a theoretical absorption spectrum obtained by the ZINDQ/S method using the geometries optimized from the AM1 and PM3 semiempirical methods. As there are experimental evidences that this system presents polaron defects, we also include the effect of the polaron type defects on the electronic structure. The results are in good agreement with the experimental ones.