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Proceedings Paper

Redox-active molecules as electrical dopants for OLED transport materials (Conference Presentation)
Author(s): Stephen Barlow; Michael A. Fusella; Samik Jhulki; Antoine Kahn; Norbert Koch; Elena Longhi; Kyung Min Lee; Xin Lin; Seth R. Marder; Karttikay Moudgil; Barry P. Rand; Chad Risko; Berthold Wegner; Fengyu Zhang

Paper Abstract

Electrical doping of organic semiconductors increases conductivity and reduces injection barriers from electrode materials, both of which effects can improve the performance of organic light-emitting diodes (OLEDs). However, the low electron affinities of typical OLED electron-transport materials make the identification of suitable n-dopants particularly challenging; electropositive metals such as the alkali metals are not easily handled and form monoatomic ions that are rather mobile in host materials, whereas molecular dopants that operate as simple one-electron reductants must have low ionization energies, which leads to severe air sensitivity. This presentation will discuss approaches to circumventing this issue by coupling electron transfer to other chemical reactivity. In particular, dimers formed by certain highly reducing organometallic sandwich compounds and organic radicals can be handled in air, yet have effective reducing potentials, corresponding to formation of the corresponding monomeric cations and contribution of two electrons to the semiconductor, of ca. –2.0 V vs. ferrocene. These values fall a little short of what is required for typical OLED materials; approaches to further extending the doping reach of these dimers will be described. One such approach involving photoirradiation of a dimer:semiconductor blend leads to metastable doping of a material with a redox potential of –2.24 V, which allows the fabrication of efficient OLEDs in which even high-workfunction electrodes, such as indium tin oxide, can be used as electron-injection contacts.

Paper Details

Date Published: 18 September 2018
Proc. SPIE 10736, Organic Light Emitting Materials and Devices XXII, 1073604 (18 September 2018); doi: 10.1117/12.2320651
Show Author Affiliations
Stephen Barlow, Georgia Institute of Technology (United States)
Michael A. Fusella, Princeton Univ. (United States)
Samik Jhulki, Georgia Institute of Technology (United States)
Antoine Kahn, Princeton Univ. (United States)
Norbert Koch, Humboldt-Univ. zu Berlin (Germany)
Elena Longhi, Georgia Institute of Technology (United States)
Kyung Min Lee, Princeton Univ. (United States)
Xin Lin, Princeton Univ. (United States)
Seth R. Marder, Georgia Institute of Technology (United States)
Karttikay Moudgil, Georgia Institute of Technology (United States)
Barry P. Rand, Princeton Univ. (United States)
Chad Risko, Univ. of Kentucky (United States)
Berthold Wegner, Humboldt-Univ. zu Berlin (Germany)
Fengyu Zhang, Princeton Univ. (United States)

Published in SPIE Proceedings Vol. 10736:
Organic Light Emitting Materials and Devices XXII
Chihaya Adachi; Jang-Joo Kim; Franky So, Editor(s)

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