2006 Volume 47 Issue 7 Pages 1703-1709
The control of nanoporous microstructure of TiO2 coating in the dye-sensitized solar cells (DSC) through preparation methods influences significantly the performance of the cells. To investigate the effect of microstructure of TiO2 deposit on the cell’s performance, in present study, vacuum cold spray (VCS) process is employed to deposit nanocrystalline TiO2 coatings on an ITO conductive glass substrate. TiO2 deposits were produced using nanosized particles of 25 nm in the diameter and composite powder composed of polyethylene glycol (PEG) and 25 nm TiO2 particles. The deposition characteristics and the microstructure of the coating are characterized by scanning electron microscopy, x-ray diffraction analysis. The performance of the cell is tested under illumination of a metal halide lamp with a radiation intensity of 600 W·m−2. It was found that a dense TiO2 coating with retention of crystal structure of powder can be deposited by vacuum cold spraying directly using nanosized TiO2 powder. A cell with TiO2 coating of 3.8 μm thick deposited directly by 25 nm powders yielded a short current density of 90.0 A·m−2 and conversion efficiency of 5.1% which was comparable with that of the wet doctor blading TiO2 coating. Using a composite powder of TiO2 with PEG, a porous TiO2 coating with a thickness up to several tens of micrometers can be deposited by vacuum cold spraying. A DSC cell of TiO2 coating deposited using a composite powder containing 41.2% PEG presented a higher short current density of 145.0 A·m−2, and conversion efficiency of 7.1%.
