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 center dot center dot center dot 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/cm(2) 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/cm(2) and an FF of 63.73%, which is so far the best performance reported for organic photovoltaic using silole-based small-molecule acceptors.

Automated summary

Two nonfused small molecular acceptors based on simple dithienosilole units have been synthesized and studied for their optical, electrochemical properties, and device performance, showing promising results when combined with the polymer PBDB-T in terms of photovoltaic efficiency.