A unified understanding of charge transport in organic semiconductors: the importance of attenuated delocalization for the carriers

Abstract

The generalized Einstein relation (GER) can unify various theoretical models and predict charge transport in OSCs with various crystallinities, by altering the variance of the density of states and the delocalization degree in a Gaussian-distributed density of states.

Transport models in disordered organic semiconductors and their application to the simulation of thin‐film transistors

“…Most of the mobility models do not account for the effect of the electric field on the hopping mechanism . The effect of the electric field is to lower the effective energetic barrier ΔE ij and consequently increase the hopping probability.…”

“…Liu et al . proposed an approach to describe the transport properties in OSCs using the generalized Einstein relation .…”

“…The shape of D ( E ) depends on the complex microscopic structure of the OSC and cannot be determined exactly. To overcome this difficulty, the authors considered the diffusion coefficient D ( E ) to be Gaussian‐like with a Gaussian width ΔD . The energetic conductivity in the LUMO band (assuming a Gaussian DOS with a Gaussian width ΔE ) is then described by …”

“…Tail states are considered to be strongly localized. By adjusting ΔE and ΔD the method can reproduce a wide range of theoretical carrier mobility models from the band transport model to the different hopping models . Figure illustrates the variation of the mobility with ΔD and T for high disorder OSCs (Fig.…”

“…Computed mobility values for different degrees of the delocalization ΔD and different temperatures for (a) highly disordered OSCs and (b) low disordered OSCs …”