Preparation and characteristics of white EL display panels

Two methods for preparing white emitting EL panels are well known in principle: (1) blending a blue and an orange emitting EL phosphor and (2) partially cascading of green EL emission with a red photoluminescent material, typically an organic fluorescent dye. Both methods have their advantages and shortcomings. Panels containing phosphor blends are readily viewed even in moderately bright ambient light but the “ white” color is reasonably stable only over limited times because the blue phosphor comnonent deteriorates faster than the orange. Cascading panels show very long lives, depending on the green EL phosphor involved, without any visible color change but these panels can be used only under restricted ambient light conditions. Brightnesses and efficiencies of both kinds of panels are about comparable