52.3: OLEDs for Lighting Applications

OLEDs for lighting applications require the combination of several properties at the same time: Large emission area, high brightness, high efficiency, long lifetime, good color stability at different brightness levels, and low cost. In order to fulfill these demands, several OLED architecture concepts are under investigation: Hybrid layered OLEDs, stacked OLEDs, pixel‐OLEDs. To achieve good color stability the diode‐units used for stacking have to be optimized. The talk focuses on hybrid OLEDs and their properties. In this context we demonstrate a phosphorescent yellow diode (combination of red and green emitters) which has an efficacy between 50 and 60 lm/W without improved light out‐coupling (ILO) and excellent color stability. Such highly optimized OLED architectures have to be combined with suitable optical out‐coupling techniques to make OLEDs ready for lighting. Optical out‐coupling techniques are briefly reviewed. We demonstrate a concept for extracting more light of an OLED using low refractive index hole transport layers.