jp067262t_si_001.pdf (542.83 kB)

Thiophene- and Selenophene-Based Heteroacenes:  Combined Quantum Chemical DFT and Spectroscopic Raman and UV−Vis−NIR Study

Download (542.83 kB)
journal contribution
posted on 05.07.2007 by Reyes Malavé Osuna, Rocío Ponce Ortiz, Toshihiro Okamoto, Yoshitake Suzuki, Shigehiro Yamaguchi, Víctor Hernández, Juan Teodomiro López Navarrete
In this article, we report the characterization of a series of thiophene- and selenophene-based heteroacenes, materials with potential applications in organic electronics. In contrast to the usual α-oligothiophenes, these annelated oligomers have a larger band gap than most semiconductors currently used in the fabrication of organic field-effect transistors (OFETs) and therefore they are expected to be more stable in air. The synthesis of these fused-ring molecular materials was motivated by the notion that a more rigid and planar structure should reduce defects (such as torsion about single bonds between α-linked units or S-syn defects) and thus improve π-conjugation for better charge-carrier mobility. The conjugational properties of these heteroacenes have been investigated by means of FT-Raman spectroscopy, revealing that π-conjugation increases with the increasing number of annelated rings. DFT and TDDFT quantum chemical calculations have been performed, at the B3LYP/6-31G** level, to assess information regarding the minimum-energy molecular structure, topologies, and absolute energies of the frontier molecular orbitals around the gap, vibrational normal modes related to the main Raman features, and vertical one-electron excitations giving rise to the main optical absorptions.