Dependence of Mobility on Density of Gap States in Organics by GAMEaS - Gate Modulated Activation Energy Spectroscopy

TL;DR

This paper introduces GAMEaS, a new technique for measuring the density of states in organic semiconductors, revealing how DOS influences mobility and device performance.

Contribution

The paper presents a novel, broadly applicable spectroscopy method, GAMEaS, to determine the density of states and relate it to mobility in organic semiconductors.

Findings

Lower DOS correlates with higher effective mobility.

Mobility up to 100 cm2/Vs at 300K observed in high-quality samples.

Sample purity significantly enhances device performance.

Abstract

We develop a broadly applicable transport-based technique, GAte Modulated activation Energy Spectroscopy (GAMEaS), for determining the density of states (DOS) in the energy gap. GAMEaS is applied to field effect transistors made from different single crystal oligomer semiconductors to extract the free-carrier mobility, u_0, from the field effect mobility, u_eff. Samples with a lower DOS exhibit higher u_eff. Values of u_0 up to 100 +/- 40 cm2/Vs at 300K are observed, showing that performance can be greatly enhanced by improving sample purity and crystal quality.