An OLED device includes a pixel having a plurality of individually addressable light emitting elements including a light emitting element for emitting white light, and one or more light emitting elements for emitting colored light; at least one of the light emitting elements being stacked on top of another...http://www.google.com.au/patents/US6909233?utm_source=gb-gplus-sharePatent US6909233 - Stacked OLED display having improved efficiency
