Comments on "Unusual Thermoelectric Behavior Indicating a Hopping to Bandlike Transport Transition in Pentacene"

TL;DR

This paper discusses unusual thermoelectric behavior in organic thin film transistors, highlighting a transition from hopping to bandlike transport at low temperatures, influenced by the density of states.

Contribution

It challenges previous assumptions by analyzing the role of the density of states in the observed transport transition at low temperatures.

Findings

Seebeck coefficient increases with carrier concentration at low temperatures.

The transition from hopping to bandlike transport occurs contrary to traditional expectations.

Density of states significantly influences the transport behavior.

Abstract

W. Chr. Germs, K. Guo, R. A. J. Janssen, and M. Kemerink [1] recently measured the temperature and concentration dependent seebeck coefficient in organic thin film transistor and found the seebeck coefficient increases with carrier concentration (corresponding to the gate voltage) in the low temperature regime. They further concluded that this unusual behavior is due to a transition from hopping transport in static localized states to bandlike transport, occurring at low temperatures. This is obviously in contrast to the previous theoretical prediction because it is widely accepted that hopping transport is more pronounced at low temperature. We will discuss the reason for this unusual behavior here and suggest that the density of states function plays an important role in concentration dependent seebeck coefficient.