Finite Size Effect on Drift Mobility and Diffusion Coefficient in Thin Organic Layers: Monte-Carlo and Analytic Modeling

Hopping transport of charge carriers in thin (< 100 nm) organic layers is modeled, using Gaussian disorder model. Monte-Carlo simulations yield considerable decrease of drift mobility with thickness of the layer, which is in good agreement with the developed analytic model. The reason is that filling of rare deep states is statistically improbable in course of transient across a thin sample. Quasi-equilibrium initial distribution is considered to omit effects of dispersive transport. Results of the work can explain disagreement in results of non-stationary and stationary measurements of transport coefficients in thin films.