Novel Plastic Substrates for Very High Efficiency OLED Lighting

In 2001, lighting was estimated to have consumed 8.2 quads (approximately 762 TWh), or about 22% of the total electricity generated in the U.S. New high efficiency solid state light sources, such as light emitting diodes (LEDS) and organic LEDs (OLEDS), are needed to reduce the ever increasing demand for energy. An OLED is potentially a cost effective diffuse light source that would compete directly with conventional incandescent light sources. However, improvements in the overall efficiency of OLEDs are still required before they can achieve their cost and performance goals ¿ $3 per 1000 lumens and 90 lumens per watt, respectively ¿ and become commercially viable products. This project will increase the total light-outcoupling efficiency of phosphorescent light emitting devices (PHOLEDs) to 50% by reducing the contrast in refractive index between the OLED active layers and the device substrate. In Phase I, a PHOLED will be fabricated on both indium-tin-oxide-coated glass and high refractive index plastic substrates, and the efficiency of devices on both substrates will be compared. The expected improvement in the outcoupling efficiency with the high index plastic substrates will be characterized. Commercial Applications and other Benefits as described by the awardee: The high index plastic should have a 25% higher outcoupling efficiency than standard glass substrates. Combined with previous results, the novel OLED device structure should show a 50% increase in light extraction efficiency, allowing OLEDs to become cost-effective in general lighting applications