In our work on organic solar cells, we address the whole bandwidth of physical and technological questions concerning organic photovoltaics. This ranges from fundamental understanding of the operating principle of organic solar cells up to the development of cell and module concepts relevant to production. We test and characterize novel organic semiconductors and analyse the efficiency potential on the basis of thorough experimental characterization in combination with optical and electrical modelling. In addition, electrical models enable us to design and optimize different module structures for specific applications. In the laboratory, novel cell and module concepts with a high potential for cost reduction are developed and implemented in roll-to-roll processes.