About energy and electron transfer processes in C₆0 /phthalocyanine films

Abstract

In the present work absorption, photoluminescence excitation and emission spectra of fullerene C₆0, and a zinc derivative of phthalocyanine (ZnPc) in solutions and in multiple-layers have been investigated. In solution, the absorption spectra of the mixtures were identical with the superposition of the absorption of components, suggesting no interaction in the ground state under the dilute concentration range used in this study. Photoluminescence emission spectra of the ZnPc solution and a mixture of C₆0 and ZnPc in a non-polar solvent showed a tendency for ZnPc aggregation. The films were prepared by casting the solution onto substrates, and were tested from layer to layer. The C₆0 film thickness dependence of photoluminescence, in the C₆0/ZnPc system was studied from the initial stages of deposition to the formation of the thick film. A series of the prepared structures was characterised. These exhibited photoluminescence bands associated with the interaction between C₆0 and ZnPc films within the bilayer structure. The photoluminescence features of these very thin C₆0 films on a ZnPc surface may be analysed in the context of a symmetry reduction at the interface, and can be discussed in terms of energy and electron transfer between C₆0 and the chromophore.

Acknowledgements The authors wish to thank the FCT (Portugal) for the award of a fellowship (BPD/1525/2000) to A.A.K.