A look on the bright side

This paper shows that the external quantum efficiency, as well as the luminous efficiency of WOLEDs, is increasing continuously. This is mainly owing to the development of phosphorescent dopants and the optimization of device structure. Presently, the luminous efficiency of WOLEDs exceeds that of incandescent lamps (typically 5-18 lm/W). Therefore, they could soon offer new possibilities of lighting sources (e.g., flexible lighting panels) and applications. Large investments have been made for WOLED development in Europe and the United States. Despite the high values ot efficiency measured on prototypes, the future commercialization of WOLEDs requires sufficient lifetimes, good color stability, and uniformity over large surfaces, together with relatively low elaboration costs.