Polarization effects in the channel of an organic field-effect transistor

TL;DR

This paper investigates how dielectric properties of the gate insulator in an organic field-effect transistor influence charge carrier dynamics, showing that high-permittivity dielectrics significantly reduce bandwidth and affect mobility.

Contribution

It provides a theoretical analysis of polarization effects on charge carriers in OFETs, highlighting the impact of gate dielectric permittivity on carrier bandwidth and mobility.

Findings

High-permittivity dielectrics halve the charge carrier bandwidth in pentacene OFETs.

Carrier mass renormalization explains dielectric effects on mobility.

Polymer gate-insulators show negligible bandwidth reduction.

Abstract

We present the results of our calculation of the effects of dynamical coupling of a charge-carrier to the electronic polarization and the field-induced lattice displacements at the gate-interface of an organic field-effect transistor (OFET). We find that these interactions reduce the effective bandwidth of the charge-carrier in the quasi-two dimensional channel of a pentacene transistor by a factor of two from its bulk value when the gate is a high-permittivity dielectric such as $(\textrm{Ta}_{2}\textrm{O}_{5})$ while this reduction essentially vanishes using a polymer gate-insulator. These results demonstrate that carrier mass renormalization triggers the dielectric effects on the mobility reported recently in OFETs.