Highly Efficient Tandem White OLED Using a Hollow Structure

Kyung Hoon Han, Kwan Kim, Yoonjay Han, Yang Doo Kim, Hyoungcheol Lim, Daihong Huh, Hyun Shin, Heon Lee, Jang Joo Kim

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


A simple fabrication method for a light extraction layer is required. In this report, an internal light extraction layer composed of a high refractive index material and an air void is fabricated in five steps. A direct printing process followed by annealing of the randomly arrayed poly(benzyl methacrylate) pillars after a planarization process using TiO2-nanoparticle dispersed resist and sol is used. These substrates are used for light extraction in white tandem organic light emitting diodes (WOLEDs). By combining the hollow structure and hemi-spherical lens, WOLEDs without and with the light extraction structures are found to show maximum external quantum efficiencies of 35.6% and 103%, respectively. The power efficiencies at 100 cd m−2 of the WOLEDs without and with the light extraction structures are found to be 26.5 and 93.2 lm W−1, respectively. A color rendering index of 86.4, correlated color temperature of 4860 K, and CIE of (0.353, 0.389) are achieved in the WOLEDs with light extraction structures.

Original languageEnglish
Article number1901509
JournalAdvanced Materials Interfaces
Issue number9
Publication statusPublished - 2020 May 1

Bibliographical note

Funding Information:
K.‐H.H. and K.K. contributed equally to this work. This work was supported by the Industrial Strategic Technology Development Program (10048317) through the Korea Evaluation Institute of Industrial Technology (KEIT), Creative Materials Discovery Program through the National Research Foundation of Korea(NRF) funded by Ministry of Science and ICT (NRF‐2018M3D1A1058972), and a Technology Innovation Program (20000887, Development of self‐healing impact‐resistant film coating material and process technology for rollable displays) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea).

Publisher Copyright:
© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


  • high refractive index
  • light extraction efficiency
  • light scattering layers
  • nanoimprint lithography
  • organic light emitting diodes

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering


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