This lecture covers the fundamentals of Organic Light Emitting Diodes (OLEDs), including their working principles, device structures, and the evolution from monolayer to multilayer devices. The instructor discusses the challenges and advancements in OLED technology, such as electron blocking layers and the impact on device efficiency. Additionally, the lecture explores the commercialization of OLEDs in displays and lighting devices, highlighting their advantages and the encapsulation process for long-term stability.