This lecture discusses the potential of solar energy to replace traditional fossil fuels, highlighting the historical perspective of energy consumption. It explores various methods of solar energy conversion, focusing on photovoltaics and the efficiency of different solar cell technologies. The lecture delves into the differences between inorganic and organic materials, emphasizing the importance of the donor-acceptor interface in organic semiconductors. It also covers the mechanisms of charge generation, the role of the solar cell microstructure, and the challenges and advancements in organic solar cell fabrication techniques.