The Research On ZnO/SnO₂ Composite Films Dye-Sensitized Solar Cells

Dye-sensitized nanocrystalline solar cell (DSC) is a new type of photoelectric chemical soalr cell with simple preparation procedure, low cost, stable photo-to-electric performance and friendly environment, which make it a good alternative of photo-to-electric devices. At present, the total efficiences of DSC based on nanoporous TiO₂ electrodes has been over 11%. But various surface states on the TiO₂ thin film results in the recombination between the photo-generated electrons and the holes, increases the dark current, and reduces the total efficiency of the DSCs. It becomes a hot issue for searching for other semiconductor oxide compound thin film to replace the TiO₂ porous film.In this paper, the dye-sensitized nanocrystalline solar cells based on the SnO₂, ZnO and ZnO/SnO₂ porous films were investigated, the primary results are shown as follow:(1) SnO₂ nanoporous film with a particle size of 3-5 nanometer was prepared from Tin tetrachloride hydrate by hydrothermal method at pH = 8-9, at 200oC for 12 hour, and then calcined at 450℃for 1 hour. Based on the film, a SnO₂ nanoelectrode and a DSC were assembled. Under irradiation of simulation sunlight (100 mW/cm²), the DSC with a short-circuit intensity of 6.12 mA/cm², open-circuit voltage of 401 mV, fill factor of 46.87% and total efficiency of 1.15% of was obtained.(2) ZnO film with a particle size of 50-100 nanometer was prepared from zinc acetate by sol-gel method, and then calcined at 500℃for 1 hour. Based on the film, a ZnO nanoelectrode and a DSC were assembled. Under irradiation of simulation sunlight (100 mW/cm2), the DSC with a short-circuit intensity of 6.24 mA/cm², open-circuit voltage of 554 mV, fill factor of 51.58% and total efficiency of 1.78% of was obtained.(3) ZnO/SnO₂ complex film with a particle size of 30 nanometer was prepared by combined sol-gel method and hydrothermal method from zinc acetate and Tin tetrachloride hydrate.When the ratio of nZn: nSn was controlled at 2, a ZnO/SnO₂ complex nanoelectrode and a DSC were assembled. Based on the film, a ZnO/SnO₂ complex nanoelectrode and a DSC were assembled. Under irradiation of simulation sunlight (100 mW/cm²), the DSC with a short-circuit intensity of 14.53 mA/cm2, open-circuit voltage of 670 mV, fill factor of 58.29% and total efficiency of 5.25% of was obtained.