Highly Efficient Photocurrent Generation from a SelfAssembled Monolayer Film of a Novel C60-Tethered 2,5Dithienylpyrrole Triad

A C60-tethered 2,5-dithienylpyrrole triad was synthesized and the self-assembled monolayer (SAM) on a gold electrode was prepared. The three-electron reduced C60 radical anions of the triad in both solution and SAM film at room temperature were detected. The redox kinetics between the C60 moieties and the gold electrode is faster compared to that of the C60 SAMs with nonconjugated flexible bridge/anchor systems, as determined by smaller peak splitting in the cyclic voltammogram. The photocurrent generated in a (Au/C60-triad/MV2+/Pt) cell upon irradiation of light is exceptionally large (3200 nA/cm2) with high quantum yield (51%). The electron-rich characteristics of the molecule and the rigid conjugated molecular framework stabilize the C60 radical anions generated during electrochemical reduction and lead to remarkable enhancement of photocurrent generation.