Synthesis and photovoltaic properties of novel (X-DADAD)n conjugated polymers with fluorene and phenylene blocks

Novel fluorene- and phenylene-based conjugated polymers with the TBTBT molecular framework consisting of the thiophene (T) and benzothiadiazole (B) building blocks have been synthesized and investigated. It has been demonstrated that the variation of X building blocks with branched side chains in (X-TBTBT)_n-type structures, as well as the introduction of fluorine into the main chain, strongly affects the optical, electronic and physicochemical properties of the obtained polymers. The phenylene-based polymer with a fluorine- loaded TBTBT block achieves a power conversion efficiency of 7% in organic solar cells, which can be further improved by optimizing the active layer morphology.