High-Performance and High-CRI OLEDs for Lighting and Their Fabrication Processes
The improvement of the basic performance makes white OLEDs the promising candidate of the next generation, environmental friendly lighting source. However, for the practical application, additional properties of higher color rendering index (CRI), long lifetime at high luminance, large area uniform light emission, and high reliability for long time operation are required. Furthermore, innovative fabrication processes specialized for OLED lighting are required to reduce the cost by improving the material utilization and productivity. We developed various technologies for OLED lighting in the Japanese governmental project “High-efficiency lighting based on the organic light-emitting mechanism” from 2007. In this project, high CRI, highly efficient and long lifetime white OLEDs were realized by optically designed two-unit structure with a fluorescent deep blue emissive unit and a green / red phosphorescent unit. A reliable encapsulation structure with high heat radiation and moisture-proof characteristics realized a stable emission at high luminance as well as long storage stability. Additionally, thermal diffusivities of organic thin films with sub-hundred nanometer thicknesses were analyzed by a “rear heating/front detection type” nanosecond thermo-reflectance method. High speed wet coating process and vacuum deposition process for very thin layers were developed to improve the accuracy, material utilization and productivity.
Pietro VINCENZINI, David S. GINLEY, Giovanni BRUNO, Attilio RIGAMONTI and Nikolay ZHELUDEV
T. Komoda et al., "High-Performance and High-CRI OLEDs for Lighting and Their Fabrication Processes", Advances in Science and Technology, Vol. 75, pp. 65-73, 2010