Fabrication of cathodic dye-sensitized solar cells using microwave plasma sintered NiO coatings

The use of microwave (MW) plasma for the sintering of metal oxide nanoparticles on conducting transparent substrates has been successfully demonstrated for the production of p-type semiconductors to be employed as photoactive materials in cathodic dye-sensitized solar cells (p-DSCs).1 In particular, we focused on NiO1,2 as photoactive cathodic material for p-DSCs. In the adopted procedure NiO nanoparticles were sprayed onto conductive fluorine-doped indium oxide covered glass and successively sintered with microwave radiation using a 2.45 GHz microwave plasma system at about 400 °C.2 Well adherent oxide layers with mesoporous morphology could be obtained via MW-sintering process as demonstrated by SEM and FIB images of NiO films with thickness in the range of 2-12 µm. The electrochemical processes of the NiO films thus obtained were studied in aqueous and anhydrous electrolytes, and compared with the behaviour of compact NiO films. Successively the mesoporous NiO samples were dye-sensitized with erythrosin B, black dye, P1 and SQ02 and tested in a sealed cell with the redox couple I2/I-.3 The resulting p-DSCs displayed efficiencies of less than 0.2 % 4 when NiO cathode had an optimum thickness value of 2.5 m.1 Studies about the photo-electrochemical behaviour of tandem DSCs5 based on MW-sintered NiO cathodes and TiO2 anodes are in progress.