Electric-field-dependent charge transport in organic thin-film transistors

This article reports the experimental study of the electric-field-dependent charge transport mechanisms in polycrystalline organic thin-film field-effect transistors. This work represents the quantitative measurement of the temperature and electric-field dependences of the mobility in organic thin-film transistors with scaled device geometry when carrier densities are at levels of practical importance. The true behavior of field-dependent mobility was extracted by minimizing contact effects consistently over a range of channel lengths. In these partially ordered systems, experimental data suggest that thermally activated and field-assisted hopping transport between disorder-induced localized states dominates over intrinsic polaronic transport seen in organic single crystals. The experimental results were found to exhibit a Frenkel-Poole-type dependence consistently over a wide range of channel lengths, fields, and temperatures.