Synthesis and evaluation of scalable D-A-D π-extended oligomers as p-type organic materials for bulk-heterojunction solar cells

Abstract

The synthesis and characterization of four novel donor-acceptor-donor π-extended oligomers, incorporating naphtha(1–b)thiophene-4-carboxylate or benzo(b)thieno(3,2-g) benzothiophene-4-carboxylate 2-octyldodecyl esters as end-capping moieties, and two different conjugated core fragments, is reported. The end-capping moieties are obtained via a cascade sequence of sustainable organic reactions, and then coupled to benzo(c)(1,2,5)thiadiazole and its difluoro derivative as the electron-poor π-conjugated cores. The optoelectronic properties of the oligomers are reported. The novel compounds revealed good film forming properties, and when tested in bulk-heterojunction organic photovoltaic cell devices in combination with PC[subscript 61]BM, revealed good fill factors, but low efficiencies, due to their poor absorption profiles. ©2020 keywords: cascade organic reactions; π-conjugated oligomers; direct arylation; organic electronics; fused aromatic rings; organic photovoltaics; bulk-heterojunction organic solar cells