Highly Planar Tetramer Acceptor Constructed by Vinyl Linkage Enables Organic Solar Cells with Outstanding Efficiency

Tetramer acceptors have great potential for organic solar cells (OSCs) in practical application due to their unique backbones fusing the advantages of the good batch-to-batch repeatability of small molecules and excellent stability approaching to polymers. However, the power conversion efficiency (PCE) of most tetramer acceptors is unsatisfactory (<19%), resulting from the twist molecular configuration influencing the molecular packing and electronic mobility. Herein, through adopting a precise synthesis approach, a tetramer 4BTP3V with vinyl linkage is developed to improve the comprehensive performance of OSCs. The vinyl linkage can effectively reduce the twist between Y units, favoring intimate π–π stacking, optimizing film-forming process, and promoting charge dynamics. Consequently, the 4BTP3V works efficiently in both binary device and ternary device. An outstanding efficiency of 19.01% is obtained for binary device, and an outstanding efficiency of 19.41% is obtained for ternary device. Furthermore, due to the strong intermolecular interaction of the extended conjugation, 4BTP3V-based device has balanced thermal-, photo-, and mechanical stability, showing excellent comprehensive performance. This work highlights the significance of designing highly planar tetramers for achieving high comprehensive performance OSCs in practical application.