Hole injection in a model fluorene-triarylamine copolymer

Hon Hang Fong, Alexis Papadimitratos, Jaehyung Hwang, Antoine Kahn, George G. Malliaras

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

Recent developments in synthesis and purification have yielded conjugated polymers with hole mobilities exceeding 0.01 cm2 V-1 s-1. Essential to harvesting the potential of these materials in organic light emitting diodes (OLEDs) is the identification of suitable ohmic contacts. Using a model fluorene copolymer that shows high-mobility, non-dispersive hole transport, it is demonstrated that electrodes commonly used as anodes in OLEDs are very poor hole injectors. Injection from Au and indium tin oxide anodes is limited by energy barriers of OJS and 0.65 eV, respectively, and the injected current is found to be temperature independent - a prediction that was not reproduced by the leading injection model for disordered organic semiconductors. Injection from a poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) anode, on the other hand, is found to become less efficient with electric field, a behavior which is currently not understood. In thinner poly[(9,9′-dioctylfluorenyl-2,7-diyl)-co-(4, 4′-(N-(4-secbutyl))diphenylamine)] films, which are of relevance to OLEDs, ohmic losses on the PEDOT:PSS layer are found to limit the flow of current These results illustrate the opportunity to further improve the performance of OLEDs as well as the challenge posed by high mobility conjugated polymers for the design of hole injection layers.

Original languageEnglish (US)
Pages (from-to)304-310
Number of pages7
JournalAdvanced Functional Materials
Volume19
Issue number2
DOIs
StatePublished - Jan 23 2009

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Fingerprint Dive into the research topics of 'Hole injection in a model fluorene-triarylamine copolymer'. Together they form a unique fingerprint.

  • Cite this

    Fong, H. H., Papadimitratos, A., Hwang, J., Kahn, A., & Malliaras, G. G. (2009). Hole injection in a model fluorene-triarylamine copolymer. Advanced Functional Materials, 19(2), 304-310. https://doi.org/10.1002/adfm.200800738