The effect of chemical modification of metal oxide surface with dye molecules in organic-inorganic hybrid solid solar cells was studied by using double layered cells consisting of poly(3-hexylthiophene) (P3HT) and a flat layer of dense TiO2. The external quantum efficiency of the chemically modified cell was nearly double that expected from the photosensitizing effect of the dye molecules. The additional increase shows that the chemical modification with dye molecules can serve not only as a photosensitizer but mainly as an energy funnel and/or an electronic mediator to significantly improve the electron injection efficiency from P3HT to TiO2. (c) 2007 American Institute of Physics.