Electric field induced charge injection or exhaustion in organic thin film transistor

TL;DR

This paper investigates how electric fields influence charge injection and depletion in organic thin film transistors by measuring conductivity in-situ, revealing that accumulation layer thickness is a few monolayers and depends on chemical species.

Contribution

It introduces a method for in-situ, continuous measurement of conductivity to directly determine depletion and accumulation layer thicknesses in organic transistors.

Findings

Depletion layer thickness can be directly measured from threshold shifts.

Accumulation layer is a few monolayers thick and independent of gate voltage.

Charge injection and exhaustion are controlled by electric fields.

Abstract

The conductivity of organic semiconductors is measured {\it in-situ} and continuously with a bottom contact configuration, as a function of film thickness at various gate voltages. The depletion layer thickness can be directly determined as a shift of the threshold thickness at which electric current began to flow. The {\it in-situ} and continuous measurement can also determine qualitatively the accumulation layer thickness together with the distribution function of injected carriers. The accumulation layer thickness is a few mono layers, and it does not depend on gate voltages, rather depends on the chemical species.