Highly efficient dye-sensitized solar cells based on HfO2 modified TiO2 electrodes

Abstract In this article, we describe the use of hafnium oxide (HfO 2 ) as a new and efficient blocking layer material to modify TiO 2 electrodes in dye sensitized solar cells. Different thicknesses of HfO 2 over-layers were prepared by simple dip coating from two different precursors and their effects on the performance of DSSCs were studied. The HfO 2 modification remarkably increases dye adsorption, resulting from the fact that the surface of HfO 2 is more basic than that of TiO 2 . Furthermore, the HfO 2 coating demonstrated increased diffusion coefficient ( D e ) and lifetime ( τ e ) of the photoelectrons, indicating the improved retardation of the back electron transfer, which increases short-circuit current ( J sc ) and open-circuit voltage ( V oc ). Thereby, the photo conversion efficiency ( η ) of the solar cell was greatly improved from 5.67 to 9.59% (an improvement of 69.02%) as the HfO 2 layer was coated over TiO 2 films.