A method of forming a polymer, the method begins by combining 4,7-bis(5-bromo-4-alkylthiophen-2-yl)-5-chloro-6-fluorobenzo[c][1,2,5]thiadiazole, [4-alkyl-5-[5-(trimethylstannyl)thiophen-2-yl]thiophen-2-yl]trimethylstannane, (3,3′-difluoro-[2,2′-bithiophene]-5,5′-diyl)bis(trimethylstannane), Pd2dba3 and P(o-tol)3 to form the polymer: In this polymer R1 and R2 are independently selected from the group consisting of a straight-chain or branched carbyl, silyl, or hydrocarbyl, a branched or cyclic alkyl with 1 to 30 atoms, a fused substituted aromatic ring, and a fused unsubstituted aromatic ring; and the ratio of x is between 0.6 to 0.8 and y is between 0.2 and 0.4.