Optical outcoupling enhancement in organic light-emitting diodes using a gradually varying refractive index dielectric structure

To provide a practical method to enhance the optical outcoupling of organic light-emitting diodes (OLEDs), we propose the use of a gradual refractive index dielectric (GRID) structure. The GRID structure of the sequentially varying composition ratio was fabricated using a sequential codeposition met...

Full description

Saved in:
Bibliographic Details
Published in:Japanese Journal of Applied Physics 2015-06, Vol.54 (6), p.62101
Main Authors: Cho, Hyun-Jun, Kim, Doo-Hoon, Lee, Ho-Nyeon
Format: Article
Language:English
Subjects:
Calcium fluoride
Dielectrics
Luminance
Organic light-emitting diodes
Patterning
Refractive index
Refractivity
Tungsten oxides
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:To provide a practical method to enhance the optical outcoupling of organic light-emitting diodes (OLEDs), we propose the use of a gradual refractive index dielectric (GRID) structure. The GRID structure of the sequentially varying composition ratio was fabricated using a sequential codeposition method. Optical outcoupling from surface plasmon polariton (SPP) modes is promoted owing to the large refractive index of WO3, and the formation of waveguide modes in the GRID structure is impeded owing to the irregular surface morphology of CaF2. The efficiency of the OLEDs was improved by more than 20% using the GRID multicathode OLED (MC-OLED) structure, without requiring an additional patterning process. In addition, the emission spectra remained almost unchanged following the introduction of the GRID MC structures, and the angular distribution of luminance became similar to that of Lambertian emission. Owing to the high performance and simple low-cost fabrication processes, the outcoupling enhancement method using a GRID structure is expected to be a practical solution to improving the luminous efficiency of OLEDs, with applications including high-performance mobile display devices and large-area televisions.
ISSN:0021-4922
1347-4065
DOI:10.7567/JJAP.54.062101