Optical interference, contrast-enhanced electroluminescent device

Abstract

A contrast enhancement for electroluminescent displays that uses optical interference is described. The reflection of ambient light from a display can be greatly reduced through the addition of thin-film optical components. In particular, a black layer system consisting of a dielectric layer and a thin absorbing layer is able to reduce the luminous reflectance from 75% to 3% when deposited next to the aluminum counterelectrode. Furthermore, with the addition of several other thin-film optical layers, the luminous reflectance can be decreased to 0.4% while also decreasing the sensitivity of the reflectance to the thicknesses of the electro-optic layers. Theoretical examples of different layer systems with and without optical components are provided. A prototype display that incorporates a black layer system was built, and a luminous reflectance of 3% was achieved.