In this paper, a ZnO/CdS/CuO:Co solar cell was prepared on a glass/indium oxide (ITO) substrate. First, we use RF-sputtering to deposit the window (ZnO) layer by optimizing the oxygen pressure while keeping the RF power at 200 W. Fourier transform infrared and X-ray reflectometry spectra were carried out, and it is found that 30% of O2 is the optimal percentage to obtain the best density and the best refractive index for the ZnO layer. The CdS layer was then deposited by the sol–gel method to align the energy bands, and a layer of CuO:Co with a thickness of 750 nm was deposited, also by reactive RF-sputtering technique. Finally, the electrical contacts were made by depositing circular silver electrodes. The obtained photovoltaic activity of device confirms that the aforementioned method is promising for further future optimizations.