We report on a strong field-dependent mobility in OFETs fabricated by using poly(2,5-bis(3-alkylthiophene-2-yl)thieno[3,2-b]thiophene) (pBTTT-C14) as the active polymer layer. Charge transport and mobilities in devices annealed in the mesophase show a more pronounced dependence on channel length as compared with as-cast devices. First, we show that the contact effects in both sets of devices are negligible from room temperature down to ~100 K. Then we show that this field-dependence is consistent with a Poole-Frenkel model of mobility. Finally, the nonlinear transport data for short channel devices is modeled consistently in the Poole-Frenkel framework, over a broad temperature range.
Citation: Journal of Applied Physics
Pub Type: Journals
charge transport, organic field-effect transistors, organic semiconductor, Poole-Frenkel effect, TFT