Light Extraction for OLED Lighting with 3-D Gradient Index

One of the major hurdles to the commercialization of OLED lighting technology is its low light extraction efficiency when compared to inorganic LEDs. Currently only ~ 30% of the light produced by the OLED can be extracted. In order to be considered as a commercially viable option, OLED efficacy has to improve dramatically. The mismatch between the refractive indices among the active layer, transparent conductive anode layer, ITO, and substrate is a major cause of light extraction inefficiency. Incorporating any high RI internal light extraction (ILE) layer that addresses this problem, can dramatically improve the efficacy and lifetime of OLED devices. This SBIR Phase I project will explore the application of a 3-dimesional gradient index (GRIN) layer for light extraction. With this structure, the device has the potential to reach the theoretical maximum extraction efficiency. Furthermore, said device will be capable of directing light to where it most needed while maintaining the desired “off-state” appearance of the `panel. Phase I of the project is to ink jet print a functional 3-dimesional gradient index layer. Commercial Applications and Other Benefits Solid-state lighting (SSL), such as light emitting diodes (LEDs) and organic light emitting diodes (OLEDs), can lower the United States’ consumption of energy used for lighting by up to 50%. Even though in terms of technological and commercial development, OLED lighting is behind LED lighting, it offers several unique advantages. OLED devices can be ultrathin, flexible, and can be manufactured by deposition over any large smooth area. Together with LED, OLED lighting can reduce carbon emissions, mercury pollution, and the US dependency on foreign oil.