Abstract Bimolecular lipid membranes are formed from solutions containing lecithin and chlorophyll-a (chl-a) in various molar ratios. Both the Mueller-Ruding technique as well as the solvent free, Montal-Mueller technique are used to form bilayers. In both methods, increasing the chl concentration produces greater photosensitivity. The photocurrent/area is about an order of magnitude higher in bilayers formed with the solvent free method, under similar conditions. From the quantum yield calculations, it appears that the higher photocurrent/area obtained with the Montal-Mueller membranes cannot be explained solely due to the greater concentration of pigment molecules in the solvent free system. The possible role of chl—chl interactions are considered.