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Title: Suppression of external quantum efficiency roll-off of nanopatterned organic-light emitting diodes at high current densities

Abstract

We developed organic light-emitting diodes (OLEDs) with nanopatterned current flow regions using electron-beam lithography with the aim of suppressing singlet–polaron annihilation (SPA). Nanopatterns composed of lines and circles were used in the current flow regions of nano-line and nano-dot OLEDs, respectively. Excitons partially escape from the current flow regions where SPA takes place. As such, current densities where external quantum efficiencies were half of their initial values (J{sub 0}) increased as line width and circle diameter were decreased to close to the exciton diffusion length. Circles were more efficient at enhancing exciton escape and increasing J{sub 0} than lines. The J{sub 0} increase in the nano-dot OLEDs containing nanopatterned circles with a diameter of 50 nm was approximately 41-fold that of a conventional OLED with a current flow region of 4 mm{sup 2}. The dependence of J{sub 0} on the size and shape of the nanopatterns was well explained by an SPA model that considered exciton diffusion. Nanopatterning of OLEDs is a feasible method of obtaining large J{sub 0}.

Authors:
;  [1]; ; ;  [2]; ;  [3];  [1];  [3]
  1. Nano-Science and Nano-Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan)
  2. Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan)
  3. JST, ERATO, Adachi Molecular Exciton Engineering Project, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan)
Publication Date:
OSTI Identifier:
22492834
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 118; Journal Issue: 15; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-8979
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANNIHILATION; CURRENT DENSITY; DIFFUSION LENGTH; ELECTRON BEAMS; LIGHT EMITTING DIODES; LINE WIDTHS; QUANTUM EFFICIENCY

Citation Formats

Kuwae, Hiroyuki, Kasahara, Takashi, JST, ERATO, Adachi Molecular Exciton Engineering Project, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Nitta, Atsushi, Yoshida, Kou, Inoue, Munetomo, Matsushima, Toshinori, Adachi, Chihaya, Center for Organic Photonics and Electronics Research, Shoji, Shuichi, Mizuno, Jun, and Research Organization for Nano and Life Innovation, Waseda University, 513 Waseda Tsurumaki-cho, Shinjuku, Tokyo 162-0041. Suppression of external quantum efficiency roll-off of nanopatterned organic-light emitting diodes at high current densities. United States: N. p., 2015. Web. doi:10.1063/1.4932139.
Kuwae, Hiroyuki, Kasahara, Takashi, JST, ERATO, Adachi Molecular Exciton Engineering Project, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Nitta, Atsushi, Yoshida, Kou, Inoue, Munetomo, Matsushima, Toshinori, Adachi, Chihaya, Center for Organic Photonics and Electronics Research, Shoji, Shuichi, Mizuno, Jun, & Research Organization for Nano and Life Innovation, Waseda University, 513 Waseda Tsurumaki-cho, Shinjuku, Tokyo 162-0041. Suppression of external quantum efficiency roll-off of nanopatterned organic-light emitting diodes at high current densities. United States. doi:10.1063/1.4932139.
Kuwae, Hiroyuki, Kasahara, Takashi, JST, ERATO, Adachi Molecular Exciton Engineering Project, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Nitta, Atsushi, Yoshida, Kou, Inoue, Munetomo, Matsushima, Toshinori, Adachi, Chihaya, Center for Organic Photonics and Electronics Research, Shoji, Shuichi, Mizuno, Jun, and Research Organization for Nano and Life Innovation, Waseda University, 513 Waseda Tsurumaki-cho, Shinjuku, Tokyo 162-0041. Wed . "Suppression of external quantum efficiency roll-off of nanopatterned organic-light emitting diodes at high current densities". United States. doi:10.1063/1.4932139.
@article{osti_22492834,
title = {Suppression of external quantum efficiency roll-off of nanopatterned organic-light emitting diodes at high current densities},
author = {Kuwae, Hiroyuki and Kasahara, Takashi and JST, ERATO, Adachi Molecular Exciton Engineering Project, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 and Nitta, Atsushi and Yoshida, Kou and Inoue, Munetomo and Matsushima, Toshinori and Adachi, Chihaya and Center for Organic Photonics and Electronics Research and Shoji, Shuichi and Mizuno, Jun and Research Organization for Nano and Life Innovation, Waseda University, 513 Waseda Tsurumaki-cho, Shinjuku, Tokyo 162-0041},
abstractNote = {We developed organic light-emitting diodes (OLEDs) with nanopatterned current flow regions using electron-beam lithography with the aim of suppressing singlet–polaron annihilation (SPA). Nanopatterns composed of lines and circles were used in the current flow regions of nano-line and nano-dot OLEDs, respectively. Excitons partially escape from the current flow regions where SPA takes place. As such, current densities where external quantum efficiencies were half of their initial values (J{sub 0}) increased as line width and circle diameter were decreased to close to the exciton diffusion length. Circles were more efficient at enhancing exciton escape and increasing J{sub 0} than lines. The J{sub 0} increase in the nano-dot OLEDs containing nanopatterned circles with a diameter of 50 nm was approximately 41-fold that of a conventional OLED with a current flow region of 4 mm{sup 2}. The dependence of J{sub 0} on the size and shape of the nanopatterns was well explained by an SPA model that considered exciton diffusion. Nanopatterning of OLEDs is a feasible method of obtaining large J{sub 0}.},
doi = {10.1063/1.4932139},
journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 15,
volume = 118,
place = {United States},
year = {2015},
month = {10}
}