In this paper, we point out the technical requirements necessary to achieve, with a co-evaporation set up, photovoltaic cells based on heterojunction (single or multiple) or interpenetrating networks of organic molecules. We describe the evaporation cell design of our home made experimental coevaporation bench and show the limitation of such experiment. Finally, ITO/ZnPc-C-60/ Al diodes were achieved, the active layer being a single heterojunction bilayer or a coevaporated layer. In the case of heterojunctions, the poor reproducibility of the results was attributed to the presence of short circuit pathways due to the C-60 layer inhomogeneity. The coevaporated layers have performances comparable to those obtain in literature without doping or additive layers. (C) 2003 Elsevier B.V. All rights reserved.