Synthetic Routes to TEG-Substituted Diketopyrrolopyrrole-Based Low Band-Gap Polymers

We report herein general synthetic routes to novel TEG-functionalized DPP-based co-polymers (TEG = triethylene glycol; DPP = diketopyrrolopyrrole) that display alternating TEG-substituted DPP moieties with various functionalized donor units; donor units contain moieties such as polythiophene segments decorated with thermocleavable tertiary esters or additional TEG chains and alkoxy-substituted benzodithiophenes. The synthetic approaches are based on Stille coupling chemistry or, for the first time for TEG-substituted DPP-based polymers, on direct heteroarylation polymerizations. Spectroscopic and electrochemical characterization as well as preliminary tests in photovoltaic cells are also reported.