(a) Spectral response of dye-sensitized solar cells based on nanoporous ZnO grown on ZnO:Al of increasing thicknesses and dyed with D149 for 2 h. (b) Evolution of the Jsc measured with the solar simulator (squares) and calculated from the spectral response (triangles) with the thickness of the nanoporous ZnO in the same coloration conditions. Jsc of the best cell is shown (empty square).