Ternary Random Strategy Applied in Active Layer of High Performance Non-Fullerene Organic Solar Cells

In recent years, there has been significant progress in non-fullerene organic solar cells (NF-OSCs) due to the rapid development of narrow-bandgap small-molecule acceptor materials and the high-performance polymer donor materials, with the power conversion efficiency (PCE) approaching 20%. However, as the design of alternating D-A copolymer materials reaches saturation, there is an urgent need to develop more efficient conjugated polymer materials. The ternary random strategy has emerged to address this challenge. The advantages of the ternary random copolymerization, including easy energy level tuning, broad and strong absorption, and high molar absorptivity, which have attracted considerable attention in the field of organic solar cells. In this review, firstly, the advantages of the ternary random copolymerization strategy in modulating polymer properties and device performance are discussed. Through this strategy, the active layer morphology can be effectively regulated and optimized, and thus the charge transfer efficiency can be improved leading to the improved PCE. Furthermore, the application of the ternary random copolymerization into NF-OSCs is summarized from the perspectives of random polymer donors and acceptors. Finally, a summary and outlook of the further development of random polymers are presented. As expected, to understand the design concept and advantages of ternary random strategy would be beneficial for the development of organic solar cells.