Abstract

Thin film electroluminescent (TFEL) devices usually consist of the following electrooptical layers: a transparent electrode, a front dielectric, a phosphor, a rear dielectric, and an opaque aluminum counter-electrode. The interfaces between these layers can reflect significant amounts of light, especially at the dielectric/aluminum interface. In certain conditions the reflected ambient light may be comparable to that emitted by the phosphor, resulting in poor readability of the device. Different methods have been previously suggested to reduce the reflectance of ambient light and hence to increase the contrast. In this work the TFEL device is considered from the viewpoint of optical thin film interference. After the introduction of additional layers, the optical constants and thicknesses of all the layers in the device are optimized to reduce the reflectance. A 4-cm by 6.5-cm panel with 40 by 64 lines has been built at the NRCC and tested at Luxel for proof-of-concept.

© 1991 Optical Society of America