OLED device having improved contrast
View Patent ↗A full-color organic light-emitting diode (OLED) device, comprising: a) a plurality of light emitting OLED pixels, each pixel having three or more color light-emitting elements for emitting different colors of light specifying a gamut and at least one additional light-emitting element for emitting a color of light within the gamut and wherein the power efficiency of the additional element is higher than the power efficiency of at least one of the three or more gamut elements; and b) a patterned neutral density filter selectively filtering the emitted light from the additional light emitting element.
1. A full-color organic light-emitting diode (OLED) device, comprising:
a) a plurality of light emitting OLED pixels, each pixel having three or more color light-emitting elements for emitting different colors of light specifying a gamut and at least one additional light-emitting element for emitting a color of light within the gamut and wherein the power efficiency of the additional element is higher than the power efficiency of at least one of the three or more gamut elements; and
b) a patterned neutral density filter selectively located only over the additional light-emitting element to selectively filter only light emitted from the additional light-emitting element.
2. The OLED device of claim 1 wherein the neutral density filter absorbs at least 10% of light in the visible spectrum.
3. The OLED device of claim 1 wherein the neutral density filter is a polarizing filter.
4. The OLED device of claim 3 wherein the polarizing filter is a circular polarizing filter.
5. The OLED device of claim 1 wherein the optical density of the neutral density filter is time-variable.
6. The OLED device of claim 5 wherein the neutral density filter is a photo-chromic, an electro-chromic light filter, or an electrophoretic light filter.
7. The OLED device of claim 5 wherein the optical density of the neutral density filter is adjusted in response to the ambient illumination incident on the OLED device.
8. The OLED device of claim 1 further comprising an additional neutral density filter filtering emitted light from at least one, but not all, of the three or more gamut specifying color light-emitting elements.
9. The OLED device of claim 1 wherein the neutral density filter comprises carbon, carbon black, pigmented inks, or dyes.
10. The OLED device of claim 1 wherein the gamut specifying color light-emitting elements comprise a broadband light emitter and differently colored color filters to emit different colors of light.
11. The OLED device of claim 10 wherein the broadband light emitter emits substantially white light.
12. The OLED device of claim 10 wherein the optical density of the neutral density filter is matched to the optical density of the color filters to provide equal ambient reflection luminance.
13. The OLED device of claim 10 wherein the optical density of the neutral density filter is matched to the optical density of the color filters to provide neutral color ambient reflection.
14. The OLED device of claim 1 further comprising a color filter filtering emitted light from the additional light-emitting element.
15. The OLED device of claim 1 wherein the gamut specifying color light-emitting elements comprise patterned colored light emitters.