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

A C 60 -tethered 2,5-dithienylpyrrole triad was synthesized and the self-assembled monolayer (SAM) on a gold electrode was prepared. The three-electron reduced C 60 radical anions of the triad in both solution and SAM film at room temperature were detected. The redox kinetics between the C 60 moieties and the gold electrode is faster compared to that of the C 60 SAMs with nonconjugated flexible bridge/anchor systems, as determined by smaller peak splitting in the cyclic voltammogram. The photocurrent generated in a (Au/C 60 -triad/MV 2+ /Pt) cell upon irradiation of light is exceptionally large (3200 nA/cm 2 ) with high quantum yield (51%). The electron-rich characteristics of the molecule and the rigid conjugated molecular framework stabilize the C 60 radical anions generated during electrochemical reduction and lead to remarkable enhancement of photocurrent generation.