Synthesis of ZnO nanopowders by DC thermal plasma for dye-sensitized solar cells

초록

Zinc oxide (ZnO) nanopowders were synthesized by DC thermal plasma process of commercially available micro-sized zinc powders (Aldrich Co., 98%, 10μm) at atmospheric pressure. The micro-sized zinc powders were vaporized in the plasma region, then subsequently this plasma processing equipment was rapidly quenched, resulting in the formation of ZnO nanopowders with a size of less than 300nm. Two different reaction gases of oxygen and carbon dioxide were used as an oxygen source and each gas flow rate was controlled as process variables. The obtained ZnO nanopowders were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). All synthesized ZnO nanopowders showed high crystalline wurtzite structures and their different morphologies were strongly dependent of the operating variables. The photocurrent-voltage (J-V) curve of the ZnO nanopowders with a dye of Ruthenium (II) 535 bis-TBA (N719, Solaronix) in redox electrolyte of methoxyacetonitrile containing 0.05 M iodine, 0.2 M lithium iodide, 0.6 M 1-hexyl-2,3-dimethyl imidazolium iodide and 0.5 M 4-tert butyl pyridine showed the overall energy conversion efficiency (η) of 2.54%, demonstrating a feasibility of the application of the mass-producible ZnO nanopowders by thermal plasma processing to DSSC.