Simple dithienosilole-based nonfused nonfullerene acceptor for efficient organic photovoltaics.

Two simple dithienosilole unit (DTS)-based nonfused small molecular acceptors (SiOC2C6–4F and SiOC2C6–4Cl) using two DTS moieties linked alkoxyl substituted benzene ring as the central core (D) and bis(5,6-difluro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene)dimalononitrile or bis(5,6-dichloro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene)dimalononitrile as the end groups have been synthesized. The optical, electrochemical properties and device photovoltaic performance of these two molecules were investigated in detail. DFT results indicates S⋯O interactions involving alkoxyl groups of benzyl rings and thienyl S atoms of DTS can act as conformational "locks" to enhance molecular planarity. when the polymer PBDB-T was chosen as the donor, the PBDB-T: SiOC2C6–4F -based device provided a high PCE of 9.68% with a V oc of 0.90 V, a J sc of 17.02 mA/cm2 and an FF of 63.00%, while the PBDB-T: SiOC2C6–4Cl -based device exhibited a PCE of 11.29% with a V oc of 0.87V, a J sc of 20.35 mA/cm2 and an FF of 63.73%, which is so far the best performance reported for organic photovoltaic using silole-based small-molecule acceptors. Simple Dithienosilole unit based nonfused small molecular acceptors based solar cells exhibited a PCE of 11.29%. Image 1 • Two dithienosilole unit-based nonfused small molecular acceptors were synthesized. • S⋯O interactions can serve as conformational "locks" to enhance π-system coplanarity. • SiOC2C6–4Cl exhibit stronger and broader absorption than that of SiOC2C6–4F. • Organic solar cells based on PBDB-T: SiOC2C6–4Cl provide a PCE of 11.29%. [ABSTRACT FROM AUTHOR]