Study of F4TCNQ dopant diffusion using transport measurements in organic semiconductors

TL;DR

This study investigates F4TCNQ dopant diffusion in organic semiconductors using in-situ transport measurements, demonstrating a simple sequential doping method that allows control over doping density and conductivity.

Contribution

It introduces a straightforward sequential doping technique for organic semiconductors, enabling controlled doping via dopant diffusion monitored through in-situ transport measurements.

Findings

Bulk doping achieved through sequential F4TCNQ deposition

Doping density controlled by F4TCNQ layer thickness

Potential for improved organic transistor performance

Abstract

In this paper, we report on electrical transport in F4TCNQ doped organic semiconductor (host) materials. By monitoring the conductance of the sample in-situ during and after deposition, we show that sequential deposition of F4TCNQ and host semiconductor results in bulk doping of the semiconductor. In addition, the doping density (and conductivity) of the host can be easily controlled by adjusting the thickness of the bottom F4TCNQ layer. This alternative scheme for doping is simpler than the conventional way of doping small molecules which involves simultaneous co-evaporation of host and dopant. In the sequential doping scheme outlined here, bulk doping of the host takes place due to rapid diffusion of F4TCNQ in the host material. The motion of F4TCNQ in the host is complex and is not always described by a simple diffusion process. In situ transport measurements provide a quick and easy way of measuring dopant diffusion in new hosts. Based on the doping results, we also outline a possible route to improved transconductance for organic thin film transistors in a manufacturing environment.