This lecture covers the fundamentals and applications of organic solar cells, focusing on topics such as the operation, excitons, bulk heterojunction, and progress in recent years. It also discusses the comparison to other PV technologies, printed power, cell efficiency, types of polymer solar cells, and processing methods. The presentation delves into organic semiconductors, excitons, and the breakthrough in bulk heterojunction solar cells, emphasizing the importance of materials and production methods for achieving economic and environmental sustainability.