The search for renewable energy sources and the efficient utilization of energy have been the most important research areas in modern science and technology. The design and development of materials that can contribute to light-harvesting, solar energy conversion and photovoltaics are important areas of research. Also of great importance is the exploration of WOLEDs for solid state lighting that could lead to a more efficient utilization of energy. This monograph consists of a collection of contributions from prominent leading scientists in the area, initiated by the organization of the SRT Workshop on WOLEDs and Organic Photovoltaics at The University of Hong Kong in January 2009. This represents a unique and irresistibly attractive account and reference for researchers in the field of WOLEDs and organic photovoltaics both from academia and industry.