Fundamental characteristic length scale for the field dependence of hopping charge transport in disordered organic semiconductors. Nenashev, A., V., Oelerich, J., O., Dvurechenskii, A., V., Gebhard, F., & Baranovskii, S., D. Physical Review B, 96(3):035204, 2017.
Fundamental characteristic length scale for the field dependence of hopping charge transport in disordered organic semiconductors [pdf]Paper  Fundamental characteristic length scale for the field dependence of hopping charge transport in disordered organic semiconductors [link]Website  abstract   bibtex   
Using analytical arguments and computer simulations we show that the dependence of the hopping carrier mobility on the electric field $\mu(F)/\mu(0)$ in a system of random sites is determined by the localization length $\alpha$ and not by the concentration of sites $N$. This result is in drastic contrast to what is usually assumed in the literature for theoretical description of experimental data and for device modeling, where $N^-1/3$ is considered as the decisive length scale for $\mu(F)$. We show that although the limiting value $\mu(F \rightarrow 0)$ is determined by the ratio $N^-1/3/\alpha$, the dependence $\mu(F)/\mu(0)$ is sensitive to the magnitude of $\alpha$ and not to $N^-1/3$. Furthermore, our numerical and analytical results prove that the effective temperature responsible for the combined effect of the electric field $F$ and the real temperature $T$ on the hopping transport via spatially random sites can contain the electric field only in the combination $eF\alpha$.

Downloads: 0