High Efficiency, White TOLED Devices for Lighting Applications

75825S General lighting is responsible for more than 20% of the energy consumption in the U.S., New broadband white-lighting sources are sought that offer significant gains in power efficiency and color quality while having less environmental impact than traditional incandescent and fluorescent lights. Recent breakthroughs in highly-efficient phosphorescent organic light-emitting device (PHOLED) technology have created an enthusiasm that this technology may someday provide such a solution. However, significant engineering challenges remain. For example, OLED extraction efficiency needs improvement in order to meet the demanding power efficiency targets of general lighting. This project will develop a higher-optical-extraction-efficiency device using transparent-cathode OLED (TOLED) technology for white lighting sources and future smart windows. Phase I simulated and fabricated a white transparent phosphorescent OLED (T-PHOLED), with light output equivalent to a conventional bottom emission OLED, and demonstrated an approximately 1 cm2 white T-PHOLED light source on a glass substrate. The resulting optical extraction was 20% greater than that for a similar conventional bottom emission device. Phase II will further improve the TOLED efficiency by optimizing the cathode transmission, replacing the conventional glass package with a monolithic mutilayer thin film encapsulation, and optimizing the design by taking advantage of microcavity effects and reduced optical losses at the air/OLED interface. Lastly, a phosphorescent TOLED lighting prototype will be fabricated to achieve greater than 25 lm/W at a luminance of 1,000 cd/m2. Commercial Applications and Other Benefits as described by the awardee: The light source should find use in diffuse lighting applications in commercial, residential, and industrial sectors. Because the product can be thin, lightweight, and transparent, it also should find use in architectural, automotive, and wearable electronic applications.