Charge transport in disordered organic solids: A Monte Carlo simulation study on the effects of film morphology

TL;DR

This study uses Monte Carlo simulations to analyze how film morphology, specifically ordered regions, affects charge mobility in disordered organic solids, revealing that increased order enhances mobility and influences its field and temperature dependence.

Contribution

It provides new insights into how ordered micro regions within disordered polymers impact charge transport, highlighting the effects of morphology on mobility and its dependencies.

Findings

Increased ordered regions raise mobility magnitude.

Mobility saturation occurs at lower fields with more order.

Mobility shows 1/T^2 temperature dependence.

Abstract

The influence of ordered regions (micro crystallites and aggregates) in the other wise disordered polymer host matrix on field and temperature dependence of mobility (\mu) has been simulated. Increase in concentration of ordered regions leads to increase in magnitude of mobility and in high field regime the saturation of the mobility occurs at lower electric field strength. The influence of different mean and standard deviation of Gaussian density of states (DOS) of ordered regions on the field dependence of mobility was studied and found to be significant only at higher concentrations. Weak influence of these parameters at low concentrations are attributed to the strong interface effects due to the difference in the standard deviation of DOS of two regions (host and ordered region) and shallow trapping effect by ordered regions. For all the parameters of ordered regions under investigation the temperature dependence of mobility (log{\mu}) and the slope of log{\mu} Vs E^{1/2} plot show 1/T^2 dependence.