Impact of functionalized polystyrenes as the electron injection layer on gold and aluminum surfaces: A combined theoretical and experimental study

Theodoros A. Papadopoulos, Hong Li, Eung Gun Kim, Jie Liu, James A. Cella, Christian M. Heller, Andrew Shu, Antoine Kahn, Anil Duggal, Jean Luc Brédas

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

At metal/organic interfaces, the insertion of an organic monolayer can significantly modify the surface properties of the substrate, especially in terms of charge injection across the interface. Herein, we study the formation of an insulating monolayer of morpholine or amine-functionalized polystyrene on Al(111) and Au(111) surfaces and its impact on surface work-function and charge injection. First-principles calculations based on Density Functional Theory have been carried out and point to a significant decrease in the work-function of modified metal surfaces; this is in very good agreement with ultraviolet photoemission spectroscopy measurements performed on the Au(111) surface. In addition, a bilayer cathode, consisting of a thin film of high-work-function metal, such as Al and Au, and a layer of amine-functionalized polystyrene, was also fabricated and tested in organic light-emitting diodes. Such bilayer structures exhibit substantially enhanced efficiency when compared with controls without the functionalized polymers. Our combined theoretical and experimental investigation gives insight into how a thin layer of a commodity polymer can be used to transform rather high-work-function metals into high-performance cathodes to provide efficient electron injection.

Original languageEnglish (US)
Pages (from-to)779-788
Number of pages10
JournalIsrael Journal of Chemistry
Volume54
Issue number5-6
DOIs
StatePublished - Jun 2014

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

Keywords

  • amines
  • density functional theory
  • electrochemistry
  • interfaces
  • polymers
  • semiconductors.

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