Advances in Solution‐Processed Multijunction Organic Solar Cells

The efficiency of organic solar cells can benefit from multi-junction device architectures in which energy losses are substantially reduced. This review describes recent (2015 to mid-2018) developments in the field of solution-processed multi-junction organic solar cells. In this time lapse various strategies have been investigated and implemented to improve the performance of these devices. Next to developing new materials and processing methods for the photoactive and interconnecting layers, specific layers or stacks have been designed to increase light absorption and improve the photocurrent by utilizing optical interference effects. These activities have resulted in power conversion efficiencies that approach those of modern thin film photovoltaic technologies. Multi-junction cells require more elaborate and intricate characterization procedures to establish their efficiency correctly and a critical view on the results and new insights in this matter are discussed. Application of multi-junction cells in photoelectrochemical water splitting and upscaling towards a commercial technology are briefly addressed.