Synthesis of conjugated polymers possessing diketopyrrolopyrrole units bearing phenyl, pyridyl, and thiazolyl groups by direct arylation polycondensation: Effects of aromatic groups in DPP on physical properties

ABSTRACT 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 semiconducting 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. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2337–2345 Direct arylation polycondensation of an EDOT derivative with dibrominated diketopyrrolopyrrole (DPP) monomers afforded conjugated polymers containing phenyl‐, pyridyl‐, and thiazolyl‐flanked DPP units. Investigation on their physical properties revealed the effects of the aromatic group in the DPP units. The polymer bearing the thiazolyl‐flanked DPP unit has a long‐wavelength absorption property and high crystallinity owing to a coplanar structure of a main chain, compared with the polymers bearing phenyl‐ and pyridyl‐flanked DPP units.