Light absorption efficiencies of photoactive multilayered films: a realistic approach for porous materials

In the present work the authors report a methodology to obtain an accurate calculation of the light absorption efficiency of hybrid photoactive layers. The photoactive layer (PAL) is a semiconductor matrix doped with a molecular species. The chosen matrix was TiO2 prepared either by sputtering or by sol-gel techniques. Zinc meso-tetraphenylporphyrin and Nile red were selected as light absorbing dopants due to their absorption spectra for solar light. The proposed methodology takes into account a detailed optical characterization of each PAL where the morphology and the porosity of the semiconductor matrix are considered. The role of direct excitation of the semiconductor could also be discriminated. Moreover, the method allows an accurate estimate of the effective light absorption efficiency of complex multilayered materials from the optical characterization of each layer separately.