Organic glasses: cluster structure of the random energy landscape and its effect on charge transport and injection

TL;DR

This paper models the energy landscape in organic glasses as a correlated Gaussian field influenced by dipoles and quadrupoles, revealing how cluster structures affect charge transport and injection.

Contribution

It introduces a simple method to estimate cluster size distribution in the energy landscape and analyzes how electrostatic disorder impacts charge mobility and injection.

Findings

Cluster structures significantly influence charge mobility.

Electrostatic disorder near electrodes alters injection properties.

Cluster size asymptotics can be estimated for deep clusters.

Abstract

An appropriate model for the random energy landscape in organic glasses is a spatially correlated Gaussian field, generated by randomly located and oriented dipoles and quadrupoles. Correlation properties of energetic disorder directly dictates the mobility dependence on the applied electric field. Electrostatic disorder is significantly modified in the vicinity of the electrode that affects injection properties. Correlated Gaussian field forms clusters. We suggest a simple method to estimate an asymptotics of the cluster distribution on size for deep clusters where a value of the field on each site is much greater than the rms disorder. Hopping transport in organic glasses in the case of high carrier density could be described in terms of the effective density-dependent temperature.