1-Aryl-4-silylmethyl[60]fullerenes: synthesis, properties, and photovoltaic performance

The efficient nucleophilic addition of aryl Grignard reagents (aryl=4-MeOC(6)H(4), 4-Me(2)NC(6)H(4), Ph, 4-CF(3)C(6)H(4), 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-MeOC(6)H(4), 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-limited current (SCLC) model. Organic photovoltaic devices with a polymer-based bulk heterojunction structure and small-molecule-based p-n and p-i-n 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).