First principles elaboration of low band gap ladder-type polymers.
Ladder-type polymers, obtained by small modifications of the atomic structure of ladder-type polythiophene, are studied using density-functional theory calculations. Within the local-density and GW approximations, it is found that upon a simple substitution of the sulfur atoms by nitrogen and boron atoms, the band structure of the resulting polymer exhibits band overlap between the occupied and the unoccupied states. However, the three-parameter Becke hybrid functional predicts these polymers to be small band gap semiconductors. Finally, results of time-dependent density-functional theory are reported on increasing length oligomers, indicating that the polymers would have very low excitation energies.
Pesant
Simon
S
Departement de Physique et Regroupement Quebecois sur les Materiaux de Pointe (RQMP), Universite de Montreal, Case Postale 6128, Succursale Centre-ville, Montreal, Quebec H3C 3J7, Canada.
Dumont
Guillaume
G
Langevin
Sébastien
S
Côté
Michel
M