Short Course 2: OLEDs: From Fundamentals to Applications

Organic light-emitting diodes (OLEDs) have established themselves as key light sources for high-end displays in mobile electronic devices as well as large TV sets. Near-ideal visual characteristics such as vivid color representation and the ability to express true black for high contrast ratio are among the advantages of OLEDs that make them stand out among several competing technologies. Even with such inherent benefits, however, the success of OLED technologies has required a significant deal of engineering effort in many different aspects. This short course will provide fundamentals needed to understand OLED technology and present some of the key efforts and breakthroughs that have made OLED technologies what they are today. OLED’s current trends and remaining challenges will also be discussed from the perspectives of the major applications. This short course will cover the fundamentals of organic semiconductors, such as charge transport mechanisms in organic semiconductors and the generation and transport of excitons in organic thin films. The different functional layers of highly efficient OLEDs are discussed, emphasizing key technologies such as injection enhancement methods and phosphorescent or thermally activated delayed fluorescence (TADF) emitters harvesting triplet excitons. Various strategies to optimize the device structure for high efficiency are also presented. The influence of the optical cavity in OLEDs on photon emission and outcoupling is described, leading to a complete description of the essential physics of OLEDs and their engineering strategies. From the application standpoint, fabrication technologies of OLED displays will be introduced and methods to realize true black and thus high-contrast-ratio displays will also be presented.