Synthesis of high-Tg hole-transporting polymers with different redox potentials and their performance in organic two-layer LEDs

Erika Bellmann, Sean E. Shaheen, Seth R. Marder, Bernard Kippelen, Robert H. Grubbs, Nasser Peyghambarian

Research output: Contribution to journalConference article

2 Scopus citations

Abstract

Organic hole transport materials are used in organic LEDs, where they substantially improve device performance if placed as a hole transport layer (HTL) between the anode and the electroluminescent layer (EL). Soluble polymeric hole transport materials with high glass transition temperatures are of particular interest, because they allow for efficient device fabrication through spin casting of the HTL, and high glass transition temperatures have been found to improve thermal and long-term stability of the device. The redox potential of the hole transport material determines the facility of charge injection at the anode/HTL and the HTL/EL interfaces, thus affecting the overall device efficiency. We have synthesized a series of soluble hole-transporting polymers with glass transition temperatures in the range of 130 °C to 150 °C. The synthetic method allows facile substitution of the hole transport functionality with electron-withdrawing and electron-donating groups, which permits tuning of the redox potential of the polymer. These polymers have been used as HTL in two-layer devices ITO/HTL/Alq/Mg. The maximum external quantum efficiency increases, if the redox potential is changed to facilitate reduction of the hole transport material at the HTL/EL interface. Electron-deficient derivatives show higher external quantum efficiencies. The device stability, however, follows the opposite trend.

Original languageEnglish (US)
Pages (from-to)322-331
Number of pages10
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume3476
StatePublished - Dec 1 1998
Externally publishedYes
EventProceedings of the 1998 Conference on Organic Light-Emitting Materials and Devices II - San Diego, CA, USA
Duration: Jul 21 1998Jul 23 1998

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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