Search Menu
Photonics Media Photonics Buyers' Guide Photonics EDU Photonics Spectra BioPhotonics EuroPhotonics Industrial Photonics Photonics Showcase Photonics ProdSpec Photonics Handbook
More News
Email Facebook Twitter Google+ LinkedIn Comments

High-Contrast Organic LED Design Targets Displays

Photonics Spectra
Nov 2005
Researchers at National Taiwan University in Taipei and at Industrial Technology Research Institute’s Electronics Research and Service Organization in Hsin-chu, Taiwan, have demonstrated an organic LED device structure that improves contrast without the incorporation of optical layers in the active region of the emitter. As described in the Oct. 3 issue of Applied Physics Letters, the approach relies on the optical characteristics of the electrodes and an antireflection coating, and it should be compatible with both top- and bottom-emitting devices for display applications.

In the top-emitting structure investigated, a molybdenum reflective bottom anode and a multilayer semitransparent top cathode of lithium fluoride, aluminum and silver created a microcavity that increased the electroluminescence efficiency by approximately 50 percent compared with conventional organic LEDs that employ a polarizer. The cathode and an antireflection coating reduced the effective reflectance in the visible from the surface of the emitter to approximately 3.9 percent. Increasing the reflectivity of the bottom electrode would further improve the efficiency, the researchers note, but it also would increase the reflectance of the structure.

In a proof-of-principle demonstration, the scientists fabricated a 240 × 320-pixel, active-matrix display using the high-contrast top-emitting organic LEDs. Under approximately 1000-l× illumination, the display exhibited higher contrast than one comprising organic LEDs with a conventional, bottom-emitting device structure.

As We Go To PressBreaking NewsindustrialIndustrial Technology Research InstituteNational Taiwan Universityorganic LED devicePresstime Bulletin

Terms & Conditions Privacy Policy About Us Contact Us
back to top
Facebook Twitter Instagram LinkedIn YouTube RSS
©2018 Photonics Media, 100 West St., Pittsfield, MA, 01201 USA,

Photonics Media, Laurin Publishing
x Subscribe to Photonics Spectra magazine - FREE!
We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.