Ferntosecond fluorescence dynamics of zinc biphenylporphine in nanocrystalline TiO2 films:: Evidence for interfacial electron transfer through space

The femtosecond fluorescence dynamics of zinc biphenylporphine (ZnBPP) were investigated in solution and in two solid-state environments - ZnBPP/glass and ZnBPP/TiO2 - with S-2 excitation (lambda(ex) = 410 nm and lambda(em) = 630 nm). Our results indicate that the transient in solution involves a persistent component that becomes completely quenched in thin-film samples; for solid films at least three decay coefficients are required to fit the transients. For ZnBPP/TiO2 films, the fluorescence was quenched significantly through J-type aggregation and interfacial electron transfer (IET) through space. Photocurrent measurements were also performed to confirm the existence of IET through space between ZnBPP molecules and TiO2 nanoparticles. (c) 2006 Elsevier B.V. All rights reserved.