Optically induced switch of the surface work function in TiO_2 /Porphyrin-C60 dyad system

FERNANDO FUNGO, MARIA E. MILANESIO, LEONIDES SERENO, EDGARDO N. DURANTINI, THOMAS DITTRICH AND LUIS OTERO

JOURNAL OF MATERIALS CHEMISTRY

ROYAL SOC CHEMISTRY

Año: 2007 p. 2107 - 2112

0959-9428

The TiO2/P–C60 (porphyrin–C60 fullerene dyad) system has been investigated by surface photovoltage spectroscopy under steady state (in the Kelvin-probe arrangement) and under chopped light illumination (in the capacitor arrangement). In contrast to TiO2 with adsorbed porphyrins (M-5-(4-carboxyphenyl)-10,15,20-tris(4-methylphenyl) porphyrin) and N3 (Ru(dcbpyH2)2(NCS)2) molecules, the TiO2/P–C60 dyad system can be switched by light between negative and positive surface charging depending on the photon energy. A mechanism involving the participation of a photoinduced intramolecular charge transfer state in the P–C60 dyad is proposed in order to explain the observed changes in the photovoltage.