The absorption of a large fraction of the incident solar radiation by the photoactive layer of dye-sensitized, liquid-junction photovoltaic cells is an important factor for achieving useful photoelectric conversion efficiencies. A model is presented that estimates the enhancement of optical absorption that can be obtained from light scattering in the porous nanocrystalline films used in these cells and from reflection at the back electrode. The model is applied to the optical characterization of two films, a transparent, and a strongly scattering porous titania sample.