Conjugated polymers containing phenyl-, pyridyl-, and thiazolyl-flanked diketopyrrolopyrrole (DPP) were synthesized by direct arylation polycondensation of 3,4-ethylenedioxythiophene derivatives and dibrominated DPP-based monomers, in order to probe the effects of the aromatic groups in the DPP units on the absorption property, energy level, and crystallinity. A polymer possessing thiazolyl-flanked DPP units was found to display long-wavelength absorption properties and higher crystallinity than the polymers bearing phenyl-and pyridyl-flanked DPP units. These features of the thiazolyl-based polymer were afforded by its coplanar structure of the main chain. The synthesized polymers showed semicon-ducting properties in organic field effect transistors and organic photovoltaics. Direct arylation polycondensation is an efficient synthetic method that affords a series of DPP-based polymers in a simple fashion and, thus, helping in a comprehensive understanding on the relationship between the aromatic groups in DPP units and their physical properties. (C) 2016 Wiley Periodicals, Inc.