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Proceedings Paper

Synthesis of high-Tg hole-transporting polymers with different redox potentials and their performance in organic two-layer LEDs
Author(s): Erika Bellmann; Sean E. Shaheen; Seth R. Marder; Bernard Kippelen; Robert H. Grubbs; Nasser Peyghambarian
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Paper 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 degrees C to 150 degrees 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 tow-layer devices ITO/HTL/Alq/Mg. The maximum external quantum efficiency increase, 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.

Paper Details

Date Published: 16 December 1998
PDF: 10 pages
Proc. SPIE 3476, Organic Light-Emitting Materials and Devices II, (16 December 1998); doi: 10.1117/12.332629
Show Author Affiliations
Erika Bellmann, California Institute of Technology (United States)
Sean E. Shaheen, Optical Sciences Ctr./Univ. of Arizona (United States)
Seth R. Marder, The Beckman Institute and Jet Propulsion Lab. (United States)
Bernard Kippelen, Optical Sciences Ctr./Univ. of Arizona (United States)
Robert H. Grubbs, California Institute of Technology (United States)
Nasser Peyghambarian, Optical Sciences Ctr./Univ. of Arizona (United States)


Published in SPIE Proceedings Vol. 3476:
Organic Light-Emitting Materials and Devices II
Zakya H. Kafafi, Editor(s)

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