A. Kadashchuk

Origin of Electric Field Dependence of the Charge Mobility and Spatial Energy Correlations in C60-Based Field Effect Transistors

We report on the influence of the lateral electric field on the charge mobility in organic field-effect transistors (OFET) based on C60 films with multigrain morphology. The experimental data were quantitatively described using a recent analytical model by accounting for the strong local electric fields in a multigrain transistor channel and for the energy correlation effects. To rationalize the presence of a correlated disorder in a non-polar C60 material, we show that randomly oriented permanent dipoles in organic gate dielectric layers can generate a significant dipolar disorder in an adjacent nonpolar semiconductor layer.

Electric field dependence of charge-carrier hopping transport at large carrier concentrations in disordered organic solids: Meyer-Neldel and Gill energies

Effective medium approach has been extended to describe the temperature dependent hopping charge-carrier mobility at arbitrary electric fields in the large carrier density transport regime. We take into account the spatial energy correlations in organic materials with Gaussian disorder. The theory is applied to describe recent experimental measurements of the electron transport properties in a C60-based OFET for different lateral electric fields FDS. Since this model is not limited to zero-field mobility, it allows a more accurate evaluation of important material parameters from experimental data measured at a given electric field. The shift of the Meyer-Neldel energy EMN upon applied lateral electric field FDS and the Gill energy EG upon the gate voltage VG in an OFET is shown to be a consequence of the spatial energy correlation effects in the organic semiconductor film. We showed that both the Meyer-Neldel and Gill energies can be used for estimating the width of the Gaussian density-of-states distribution.