By studying the regio- and chemoselectivity of fluoro-substituted thienothiophene and benzodithiophene copolymers, we found polymers made from conventional one-pot polycondensation reaction consist of two distinctly different segments with a ratio of 0.36/0.64. Through further comparative Studies of neat regioregular polymers based On each individual, segment, we have identified the specific segment that contributes to the superior absorption, packing order, and charge mobility in the corresponding polymers. The unique structure-property relationships are the result of cooperative molecular arrangement of the key segment and noncovalent interaction between the fluor group and the aromatic proton on the thiophene side-chain of the polymers.