Low-cost polymer acceptors with noncovalently fused-ring backbones for efficient all-polymer solar cells

The polymerization of fused-ring acceptors (FRAs) to afford their corresponding polymeric acceptors for high-performance all-polymer solar cells (all-PSCs) has achieved remarkable progress in the past few years. However, due to the high degree of synthetic complexity for the monomer, the high-cost of these polymeric acceptors may limit their commercial applications. Thus, it is urgent to develop inexpensive and high-performance polymeric acceptors for all-PSCs. Herein, two novel polymeric acceptors (PBTzO and PBTzO-2F) have been designed and synthesized by copolymerization of noncovalently fused ring acceptors (NFRAs), which were employed in all-PSCs for the first time. Upon introducing the “noncovalently conformational locks (NoCLs)” in the backbone and selective fluorination of the end-group, photophysical and electrical properties, and solid-state packing properties of the NFRAs have been rationally tuned. As a result, the PBDB-T:PBTzO-2F based devices presented an excellent power conversion efficiency (PCE) of 11.04%, much higher than that of PBTzO based ones due to the increased charge generation and extraction, improved hole transfer and carrier mobilities, and reduced energy loss. More importantly, PBTzO-2F exhibited a much lower synthetic complexity (SC) index and higher figure-of-merit (FOM) values than the highperformance fused-ring acceptor based polymer acceptors (FRA-PAs) due to the simpler structures and more effective synthesis. This contribution provided a novel idea to achieve low-cost and high-performance all-PSCs.