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Title: Alternative p-doped hole transport material for low operating voltage and high efficiency organic light-emitting diodes

Abstract

We investigate the properties of N,N′-[(Diphenyl-N,N′-bis)9,9,-dimethyl-fluoren-2-yl]-benzidine (BF-DPB) as hole transport material (HTL) in organic light-emitting diodes (OLEDs) and compare BF-DPB to the commonly used HTLs N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD), 2,2′,7,7′-tetrakis(N,N′-di-p-methylphenylamino)-9,9′-spirobifluorene (Spiro-TTB), and N,N′-di(naphtalene-1-yl)-N,N′-diphenylbenzidine (NPB). The influence of 2,2′-(perfluoronaphthalene-2,6-diylidene)dimalononitrile (F6-TCNNQ p-dopant) concentration in BF-DPB on the operation voltage and efficiency of red and green phosphorescent OLEDs is studied; best results are achieved at 4 wt. % doping. Without any light extraction structure, BF-DPB based red (green) OLEDs achieve a luminous efficacy of 35 .1 lm/W (74 .0 lm/W) at 1000 cd/m{sup 2} and reach a very high brightness of 10 000 cd/m{sup 2} at a very low voltage of 3.2 V (3.1 V). We attribute this exceptionally low driving voltage to the high ionization potential of BF-DPB which enables more efficient hole injection from BF-DPB to the adjacent electron blocking layer. The high efficiency and low driving voltage lead to a significantly lower luminous efficacy roll-off compared to the other compounds and render BF-DPB an excellent HTL material for highly efficient OLEDs.

Authors:
; ; ;  [1];  [1]
  1. Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Str. 1, 01062 Dresden (Germany)
Publication Date:
OSTI Identifier:
22304437
Resource Type:
Journal Article
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 105; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0003-6951
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BENZIDINE; BRIGHTNESS; DEPLETION LAYER; DOPED MATERIALS; ELECTRIC POTENTIAL; EXTRACTION; HOLES; INJECTION; LIGHT EMITTING DIODES; ORGANIC COMPOUNDS; P-TYPE CONDUCTORS; VISIBLE RADIATION

Citation Formats

Murawski, Caroline, Fuchs, Cornelius, Hofmann, Simone, Leo, Karl, Gather, Malte C., and SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS Scotland. Alternative p-doped hole transport material for low operating voltage and high efficiency organic light-emitting diodes. United States: N. p., 2014. Web. doi:10.1063/1.4896127.
Murawski, Caroline, Fuchs, Cornelius, Hofmann, Simone, Leo, Karl, Gather, Malte C., & SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS Scotland. Alternative p-doped hole transport material for low operating voltage and high efficiency organic light-emitting diodes. United States. https://doi.org/10.1063/1.4896127
Murawski, Caroline, Fuchs, Cornelius, Hofmann, Simone, Leo, Karl, Gather, Malte C., and SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS Scotland. Mon . "Alternative p-doped hole transport material for low operating voltage and high efficiency organic light-emitting diodes". United States. https://doi.org/10.1063/1.4896127.
@article{osti_22304437,
title = {Alternative p-doped hole transport material for low operating voltage and high efficiency organic light-emitting diodes},
author = {Murawski, Caroline and Fuchs, Cornelius and Hofmann, Simone and Leo, Karl and Gather, Malte C. and SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS Scotland},
abstractNote = {We investigate the properties of N,N′-[(Diphenyl-N,N′-bis)9,9,-dimethyl-fluoren-2-yl]-benzidine (BF-DPB) as hole transport material (HTL) in organic light-emitting diodes (OLEDs) and compare BF-DPB to the commonly used HTLs N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD), 2,2′,7,7′-tetrakis(N,N′-di-p-methylphenylamino)-9,9′-spirobifluorene (Spiro-TTB), and N,N′-di(naphtalene-1-yl)-N,N′-diphenylbenzidine (NPB). The influence of 2,2′-(perfluoronaphthalene-2,6-diylidene)dimalononitrile (F6-TCNNQ p-dopant) concentration in BF-DPB on the operation voltage and efficiency of red and green phosphorescent OLEDs is studied; best results are achieved at 4 wt. % doping. Without any light extraction structure, BF-DPB based red (green) OLEDs achieve a luminous efficacy of 35 .1 lm/W (74 .0 lm/W) at 1000 cd/m{sup 2} and reach a very high brightness of 10 000 cd/m{sup 2} at a very low voltage of 3.2 V (3.1 V). We attribute this exceptionally low driving voltage to the high ionization potential of BF-DPB which enables more efficient hole injection from BF-DPB to the adjacent electron blocking layer. The high efficiency and low driving voltage lead to a significantly lower luminous efficacy roll-off compared to the other compounds and render BF-DPB an excellent HTL material for highly efficient OLEDs.},
doi = {10.1063/1.4896127},
url = {https://www.osti.gov/biblio/22304437}, journal = {Applied Physics Letters},
issn = {0003-6951},
number = 11,
volume = 105,
place = {United States},
year = {2014},
month = {9}
}