Low Band Gap Thiophene−Perylene Diimide Systems with Tunable Charge Transport Properties

Perylenediimide−pentathiophene systems with varied architecture of thiophene units were synthesized. The photophysical, electrochemical, and charge transport behavior of the synthesized compounds were studied. Both molecules showed a low band gap of ∼1.4 eV. Surprisingly, the molecule with pentathiophene attached via β-position to the PDI unit upon annealing showed a predominant hole mobility of 1 × 10−4 cm2 V−1 s−1 whereas the compound with branched pentathiophene attached via β-position showed an electron mobility of 9.8 × 10−7 cm2 V−1 s−1. This suggests that charge transport properties can be tuned by simply varying the architecture of pentathiophene units.