Electron transport in back contact dye-sensitized solar cells

The electron transport properties of a back contact dye-sensitized solar cell (BCDSC) were investigated in comparison with a conventional DSC. It was found that the BCDSC had a lower short circuit current density (J(SC)) at the same thickness of TiO(2) film and that Jsc was not proportional to the thickness of the TiO(2) film. Calculation of electron transport length in the TiO(2) film suggested that the injected electron travels a longer distance to the electrode in the BCDSC than in the DSC. TiCl(4) treatment of the TiO(2) film produced a marked improvement of the Jsc value in the BCDSC due to an increase in the electron diffusion coefficient of the TiO(2) film, whereas the J(SC) of the DSC remained almost unchanged. It is clear that the value of Jsc in the BCDSC is more dependent on the electron transport properties of the TiO(2) film than in the DSC. Under standard AM 1.5 irradiation (100 mW cm(-2)), a BCDSC with N719 dye yielded an overall conversion efficiency of 8.0%. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.2975182]