Photocurrent Generation in Thin SnO₂Nanocrystalline Semiconductor Film Electrodes from Photoinduced Charge-Separation State in Porphyrin−C₆₀Dyad

The generation of photoelectrical effects through the spectral sensitization of wide band gap (SnO 2 ) nanostructured semiconductor electrode by the excitation of a novel porphyrin−fullerene ( P − C 60 ) dyad is reported. P − C 60 was synthesized from 5-(4-amidophenyl)-10,15,20-tris(4-methoxylphenyl) porphyrin ( P ) linked to 1,2-dihydro-1,2-methoxyphenyl [60]-61-carboxilic acid ( acid-C 60 ) by an amide bond. Anodic photocurrents and photovoltages are observed under visible irradiation of ITO/SnO 2 / P − C 60 electrodes, although the porphyrin fluorescence is strongly quenched by the C 60 moiety in the dyad. The photocurrent generation quantum yield of the dyad P − C 60 is around twice higher than the yield of the porphyrin moiety at the same wavelength (Soret band). A mechanism involving the formation of an intramolecular photoinduced charge-transfer state is proposed to explain the efficiency in the generation of photoelectrical effect.