Designing High-Performance Wide Bandgap Polymer Donors by the Synergistic Effect of Introducing Carboxylate and Fluoro Substituents

Controlling the energy levels and aggregation behavior of conjugated polymers is pivotal for constructing high-performance organic solar cells. To achieve this goal, we designed and synthesized three D–A alternating wide bandgap polymers (reg-PThE, reg-PThE-1F, and reg-PThE-2F) by synergistic introduction of carboxylate and fluoro substituents. Further investigations demonstrate that the reg-PThE-1F:BTP-eC9-4F blend film could form nanoscale phase separation, and the corresponding devices exhibit improved exciton dissociation and charge collection and higher and more balanced charge transport mobilities. Hence, an impressive PCE of 16.40% can be achieved for reg-PThE-1F:BTP-eC9-4F-based devices; especially, the PCEs of tenary devices are further improved to 17.78% or 18.64% by adding reg-PThE-1F into different binary systems. These results are among the highest PCEs based on polymer donors with carboxylate-substituted thiophene. Our work paves an efficient way to designing high-performance conjugated polymer by synergistic introduction of carboxylate and fluoro substituents.