In a light-to-photocurrent conversion system based on a C-60-porphyrin bilayer prepared by electrostatic alternate adsorption, porphyrin units in a porphyrin polymer have been isolated by cyclodextrin utilizing the host-guest interaction. In this system, a high quantum yield was achieved by suppression of self-quenching of porphyrin units. (C) 2003 Elsevier Science Ltd. All rights reserved.