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 J SC 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 J SC 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 J SC 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%.