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Hole Transport Layer Microroughening for Waveguide Mode Extraction in Organic Light‐Emitting Diodes
Author(s) -
Saha Rony,
Lyashenko Dmitry A.,
Zakhidov Alex A.
Publication year - 2022
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.202100872
Subject(s) - oled , materials science , common emitter , phosphorescence , optoelectronics , diode , scattering , layer (electronics) , biphenyl , coupling (piping) , luminous efficacy , optics , chemistry , nanotechnology , physics , organic chemistry , fluorescence , metallurgy
Herein, simple and scalable approach to enhance the out‐coupling efficiency in organic light‐emitting diodes (OLEDs) is presented. By exposing the 4,4′‐bis[ N ‐(1‐naphthyl‐1‐)‐ N ‐phenylamino]‐biphenyl (NPB) hole transport layer to hydrofluoroether (HFE) solvent for several minutes, a controllable microroughening of the film is achieved, which results in the formation of random scattering centers in the OLED structure. Optimized NPB microroughening for phosphorescent OLED with Ir(ppy)3 emitter leads to luminous efficacy improvement of 23% (from 64 to 79 lm W −1 at 1000 cd m −2 ) without additional external out‐coupling. Angular resolved spectroscopy of the OLED with an internal scattering layer reveals constant color almost independent of the viewing angle and Lambertian intensity distribution.