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

Hiroyuki Kuwae, Atsushi Nitta, Kou Yoshida, Takashi Kasahara, Toshinori Matsushima, Munetomo Inoue, Shuichi Shoji, Jun Mizuno, Chihaya Adachi

Research output: Contribution to journalArticle

16 Citations (Scopus)

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 (J0) 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 J0 than lines. The J0 increase in the nano-dot OLEDs containing nanopatterned circles with a diameter of 50nm was approximately 41-fold that of a conventional OLED with a current flow region of 4mm2. The dependence of J0 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 J0.

Original languageEnglish
Article number155501
JournalJournal of Applied Physics
Volume118
Issue number15
DOIs
Publication statusPublished - 2015 Oct 21

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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