Hetero-multilayers composed of porphyrin-containing poly(isobutyl methacrylate) (PiBMA) and polyimide (PI) monolayers were prepared by using the Langmuir-Blodgett technique, and the interlayer electron transfer process from photo-excited porphyrins to pyromellitic diimide moieties in PI layers was observed by fluorescence spectroscopy. The efficiency of the electron transfer showed strong dependence on the number of PI layers, suggesting the presence of defects in the PI plane, which were filled with PI after the successive deposition of PI monolayers. The three-dimensional and two-dimensional active sphere models (Perrin model) well explained the interlayer electron transfer phenomena. We discussed the nano-structures of the multilayer films in terms of the thickness of each layer and the location of hydrophobic porphyrins in the PiBMA monolayer. (c) 2006 Elsevier B.V. All rights reserved.