Increase in electron scattering length in PEDOT:PSS by a triflic acid post-processing

Dominik Farka,B Bruckner,Petr Klapetek,D Roth,P Bauer,H Coskun,P Stadler,N Serdar Sariciftci

doi:10.1007/s00706-017-1973-1

Abstract

A stringent limitation in many optoelectronic devices, such as solar cells and light emitting diodes, is the intrinsic need for a transparent electrode. Uniting relevant aspects, indium tin oxide (ITO) is often the material of choice, however, alternatives are sought and being in particular found in conductive polymers. In this work, we present a novel doping strategy to arrive at highly conducting polymeric material based on poly-3,4-ethylenedioxythiophene (PEDOT). Based on commercial high conductivity PEDOT:PSS (Clevios PH 1000), and a post processing with aqueous triflic acid delivers a material that is both transparent and of low resistivity (5.23 × 10−4 Ω cm). Furthermore, this material retains its conductive character over a large temperature range, indicating metallic behaviour. This is further supported by positive magnetoconductance effects at low temperatures (1.8–10 K) and extended mean free paths of the conduction electrons are observed—evidencing for a metallic state in this polymer.Graphical abstract

Highlights

In recent years, the rise of consumer electronics with liquid crystal displays, organic light emitting diode (OLED)based displays [1], OLED-based home lighting [2], and the introduction of concepts such as photovoltaic windows [3] led to a dramatic increase in demand for transparent electrode materials
We compared three materials based on commercial PEDOT:PSS (Clevios PH1000): plain PEDOT:PSS, PEDOT:PSS*, and PEDOT:TA
As PEDOT:TA already showed metallic fingerprints in the form of a rather low and flat resistivity-temperature profile we looked for magnetoresistance behaviour at low temperatures, typical for metals

Summary

Introduction

The rise of consumer electronics with liquid crystal displays, organic light emitting diode (OLED)based displays [1], OLED-based home lighting [2], and the introduction of concepts such as photovoltaic windows [3] led to a dramatic increase in demand for transparent electrode materials. Based on commercial high conductivity PEDOT:PSS (Clevios PH 1000), and a post processing with aqueous triflic acid delivers a material that is both transparent and of low resistivity (5.23 9 10-4 X cm). This material retains its conductive character over a large temperature range, indicating metallic behaviour.

Results

Conclusion