Efficient wide bandgap all-polymer solar cells benefiting from a random n-type copolymers strategy

A series of random donor-acceptor conjugated polymers with naphthalene diimide and thiophene units were designed and synthesized with varying difluorothiophene (FTh) substitution. In comparison with the nonfluorinated polymer F0, FTh-containing random polymers exhibit increased molecular interaction in solution state as well as enhanced solid state ordering. However, higher FTh content leads to unfavorable decrease in polymer solubility. When incorporated into all-polymer solar cells (all-PSCs) using PT8 as the donor, the crystallinity between donor and acceptor polymer was optimized using random copolymer strategy, and a best PCE of 9.04% was achieved with 10% FTh substitution, which is among the highest reports of wide bandgap all-PSCs. We believe that these findings will further provide insight into the control of polymer-polymer blend with desirable optoelectronic properties.

Automated summary

A series of random donor-acceptor conjugated polymers with varying difluorothiophene (FTh) substitution were designed and synthesized, achieving a best power conversion efficiency of 9.04% through optimizing crystallinity. This research provides insight into controlling polymer-polymer blends with desirable optoelectronic properties.