On January 8^th, Prof. Henry Yan, Associate Professor of the Hong Kong University of Science and Technology, delivered a lecture entitled “Toward next-generation organic solar cells that are efficient, low-cost and environmentally friendly” and answered questions from IAS students.                        

Prof. Yan said at the lecture that, the difficulty in controlling the morphology is the biggest bottleneck for the development of organic solar cells. The difficulty in controlling the morphology is the biggest bottleneck for the development of organic solar cells. A method for forming an ideal macromolecular - fullerene film topography is proposed, which makes the polymer have higher crystallinity and smaller phase separation scale. This method has been used to develop more than ten material systems, with the photoelectric conversion efficiency exceeding 10% and the highest efficiency reaching 11.7%, breaking the world record in the field of organic solar cells. An organic solar cell system based on non-fullerene receptors was also discovered. The charge separation driving force of this system is basically zero, but the charge separation is fast and efficient. For the first time, the non-fullerene system achieved 9.5% photoelectric conversion efficiency and nearly 90% internal quantum conversion efficiency, while only 0.55V voltage loss was maintained. The realization of this system indicates that organic solar cells may eventually break through the efficiency of 18-20%, creating a new phase of the development of organic solar cells. At the end of the lecture, Prof. Yan and teachers and students from IAS, all shared their own learning experience on scientific research.