A greener electrodeposition recipe for ZnO films

Electrodeposition of ZnO films can be performed in an aqueous solution using a greener recipe, where the solution can be reused for multiple deposition runs. The solution in this greener recipe contains KCl to provide electrical conductivity to allow the deposition reactions. A Zn foil serves as the Zn source, which dissolves during the deposition. O₂ is bubbled into the solution as the oxygen source. This recipe eliminates concentration change in the solution as deposition proceeds, making the solution reusable. Multiple deposition runs for ZnO films in the same solution have been demonstrated. X-ray diffraction, optical transmittance and absorption spectra reveal that all the obtained ZnO films have similar structural and optical properties. They display high transmittance of ∼80% and low absorbance of ∼10%. Moreover, an initial Zn²⁺ concentration in the solution is required, not to serve as a Zn source but to facilitate the deposition.