Rapid Deposition of Photocatalytic Oxide Film by Liquid Feedstock Injection TPCVD in Open Air

In order to develop a functional film deposition process with high deposition rate, as a basic study, deposition of titanium oxide (TiO₂) and zinc oxide (ZnO) films by thermal plasma chemical vapor deposition (CVD) in the air was carried out. As ingredient, ethanol-diluted titanium tetra butoxide and zinc acetate solution were used for TiO₂ and ZnO deposition, respectively. To investigate the effects of feedstock concentration on the films´ structures and photocatalytic property, film deposition with various concentration of feedstocks and photocatalytic tests (i.e., wettability test and methylene-blue decoloration test) were conducted. Consequently, in the cases of both films´ deposition, as the case of the CVD process, film structure could be changed from particle accumulated to columnar by decreasing the zinc acetate/ethanol ratio. Not only crystallized film but also amorphous film could be deposited, depending on deposition distance. In the case of crystallized film, photocatalytic properties were confirmed in the films by the methylene-blue decoloration test and wettability test. When the TiO₂ film was applied to the photoelectronics device of dye-sensitized solar cell, the cell could generate an electromotive force of 0.13 V, which was almost the same voltage as the ready-made one. From these results, this process was found to have a high potential for a high-rate functional film deposition process conducted in the air