Work function control of hole-selective polymer/ITO anode contacts: An electrochemical doping study

Research output: Contribution to journalArticle

46 Scopus citations

Abstract

We present a novel method for electrodeposition of ultra-thin films of poly-3-hexylthiophene (e-P3HT) on chemically modified indium-tin oxide (ITO) electrodes, to produce a hole-selective contact with an easily tuned work function (Φ), as demonstrated by a combination of spectroelectrochemistry and ultraviolet photoemission spectroscopy (UPS). Selective contacts for optimized charge injection have become essential components for both thin film organic light emitting diodes (OLEDs) and organic photovoltaics (OPVs). Electrochemically doped e-P3HT thin films, using counter ions such as PF 6- do not suffer from stability issues associated with more "acidic" polymer layers (e.g. PEDOT:PSS). By controlling the oxidation state of the e-P3HT film via electrochemical doping we control the charge density within the film, resulting in an increase in work function with an increase in degree of oxidation. The method of electrochemical formation and doping of the e-P3HT film, using either constant potential step (CA) versus pulsed-potential step (PPS) protocols, has a significant secondary impact on the work function, as a result of the interface dipole effects from entrapment of these counter ions in the near-surface region of the polymer film. These results have significance for the performance of both OLEDs and OPVs built on these doped e-P3HT layers.

Original languageEnglish (US)
Pages (from-to)2672-2679
Number of pages8
JournalJournal of Materials Chemistry
Volume20
Issue number13
DOIs
StatePublished - Mar 23 2010

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry

Fingerprint Dive into the research topics of 'Work function control of hole-selective polymer/ITO anode contacts: An electrochemical doping study'. Together they form a unique fingerprint.

Cite this