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Extracting Light from Polymer Light‐Emitting Diodes Using Stamped Bragg Gratings
Author(s) -
Ziebarth J. M.,
Saafir A. K.,
Fan S.,
McGehee M. D.
Publication year - 2004
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200305070
Subject(s) - materials science , optoelectronics , light emitting diode , optics , lithography , grating , waveguide , diode , absorption (acoustics) , coupling (piping) , oled , bragg's law , fiber bragg grating , layer (electronics) , diffraction , nanotechnology , wavelength , physics , metallurgy , composite material
In this paper, we describe a method for increasing the external efficiency of polymer light‐emitting diodes (LEDs) by coupling out waveguided light with Bragg gratings. We numerically model the waveguide modes in a typical LED structure and demonstrate how optimizing layer thicknesses and reducing waveguide absorption can enhance the grating outcoupling. The gratings were created by a soft‐lithography technique that minimizes changes to the conventional LED structure. Using one‐dimensional and two‐dimensional gratings, we were able to increase the forward‐directed emission by 47 % and 70 %, respectively, and the external quantum efficiency by 15 % and 25 %.