1-Aryl-4-Silylmethyl[60]fullerenes: Synthesis, Properties, and Photovoltaic Performance

The efficient nucleophilic addition of aryl Grignard reagents (aryl=4-MeOC6H4, 4-Me2NC6H4, Ph, 4-CF3C6H4, and thienyl) to C-60 in the presence of DMSO produced 1,2-arylhydro[60]fullerenes after acid treatment. The reactions of the anions of these arylhydro[60]fullerenes with either dimethylphenylsilylmethyl iodide or dimethyl(2-isopropoxyphenyl)silylmethyl iodide yielded the target compounds, 1-aryl-4-silylmethyl[60]fullerenes. The properties and structures of these 1-aryl-4-silylmethyl[60]fullerenes (aryl=4-MeOC6H4, thienyl) were examined by electrochemical studies, X-ray crystallography, flash-photolysis time-resolved microwave-conductivity (FP-TRMC) measurements, and electron-mobility measurements by using a space-charge-limit-ed current (SCLC) model. Organic photovoltaic devices with a polymer-based bulk heterojunction structure and small-molecule-based p-n and p-in heterojunction configurations were fabricated by using 1-aryl-4-silylmethyl[60]fullerenes as an electron acceptor. The most efficient device exhibited a power-conversion efficiency of 3.4% (short-circuit current density: 8.1 mA/cm(2), open-circuit voltage: 0.69 V, fill factor: 0.59).