Tailor-made nanostructures bridging chaos and order for highly efficient white organic light-emitting diodes

Yungui Li; Milan Kovačič; Jasper Westphalen; Steffen Oswald; Zaifei Ma; Christian Hänisch; Paul-Anton Will; Lihui Jiang; Manuela Junghaehnel; Reinhard Scholz; Simone Lenk; Sebastian Reineke

doi:10.1038/s41467-019-11032-z

Tailor-made nanostructures bridging chaos and order for highly efficient white organic light-emitting diodes

Nat Commun. 2019 Jul 5;10(1):2972. doi: 10.1038/s41467-019-11032-z.

Authors

Affiliations

¹ Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Nöthnitzer Str. 61, 01062, Dresden, Germany.
² University of Ljubljana, Faculty of Electrical Engineering, Tržaška 25, 1000, Ljubljana, Slovenia.
³ Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, Winterbergstraße 28, Dresden, 01277, Germany.
⁴ Institute for Complex Materials, Leibniz IFW Dresden, Helmholtzstraße 20, Dresden, 01069, Germany.
⁵ Center for Advanced Low-dimension Materials, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, 201620, Shanghai, China.
⁶ College of Chemistry and Chemical Engineering, Central South University, 410083, Changsha, China.
⁷ Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Nöthnitzer Str. 61, 01062, Dresden, Germany. sebastian.reineke@tu-dresden.de.

Abstract

Organic light-emitting diodes (OLEDs) suffer from notorious light trapping, resulting in only moderate external quantum efficiencies. Here, we report a facile, scalable, lithography-free method to generate controllable nanostructures with directional randomness and dimensional order, significantly boosting the efficiency of white OLEDs. Mechanical deformations form on the surface of poly(dimethylsiloxane) in response to compressive stress release, initialized by reactive ions etching with periodicity and depth distribution ranging from dozens of nanometers to micrometers. We demonstrate the possibility of independently tuning the average depth and the dominant periodicity. Integrating these nanostructures into a two-unit tandem white organic light-emitting diode, a maximum external quantum efficiency of 76.3% and a luminous efficacy of 95.7 lm W^-1 are achieved with extracted substrate modes. The enhancement factor of 1.53 ± 0.12 at 10,000 cd m^-2 is obtained. An optical model is built by considering the dipole orientation, emitting wavelength, and the dipole position on the sinusoidal nanotexture.