Photocurrent generation in thin SnO2 nanocrystalline semiconductor film electrodes from photoinduced charge-separation state in porphyrin-C60 dyad

The generation of photoelectrical effects through the spectral sensitization of wide band gap (SnO2) 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/SnO2/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.