Charge recombination reduction in dye-sensitized solar cells by means of an electron beam-deposited TiO2 buffer layer between conductive glass and photoelectrode

A thin anatase titanium dioxide compact film was deposited by electron beam evaporation as buffer layer between the conductive transparent electrode and the porous TiO2-based photoelectrode in dye-sensitized solar cells. The effect of such a buffer layer on the back transfer reaction of electrons to tri-iodide ions in liquid electrolyte-based cells has been studied by means of both electrochemical impedance spectroscopy and open circuit photovoltage decay analysis. The influence of the thickness has been also investigated and an increment in overall quantum conversion efficiency η as high as + 31% with respect to the standard cell – fabricated onto an uncoated conductive glass – has been revealed in the case of a 120 nm thick buffer layer.