Progress of organic photovoltaics towards 20% efficiency

Organic photovoltaic (OPV) technology is flexible, lightweight, semitransparent and ecofriendly, but it has historically suffered from low power conversion efficiency (PCE). However, since 2015, the materials design and PCE of OPV devices have been markedly optimized, and there is now an increasing understanding of OPV optoelectronic processes and blending morphology within the bulk heterojunction framework. In this Review, we survey OPV technology, discussing progress in enhancing the PCE and in understanding the relationship between structure and performance. This progress includes the development of emerging OPV materials and techniques for manipulation and characterization of thin-film morphology. Furthermore, we address the practical application issues ahead of OPV technology, showcasing strategies for improving device stability, fabricating large-area modules and realizing device encapsulation. Finally, we highlight future research directions, including the use of machine learning for material design and synthesis, device fabrication optimization, and prediction and optimization of device performance.