This work introduces the synthesis and the characterization of N-doped TiO2 and Co3O4 thin films prepared via DC reactive magnetron sputtering technique. N-doped TiO2 thin films was deposited on indium-tin oxide (ITO) conducting substrate at different nitrogen ratios, then the Co3O4 thin film was deposited onto the N-doped TiO2 layer to synthesize a double-layer TiO2-N/Co3O4 Photoelectrochromic device. Several techniques were used to characterize the produces which are x-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), Fourier-transform infrared (FTIR) spectroscopy and UV–Vis spectroscopy. The Photoelectrochromic device was characterized by UV–Vis spectroscopy and the results show that the double-layer N-doped TiO2/Co3O4 was sensitive to light, that’s due to the photogenerated holes in the valence band of photocatalyst (N-doped TiO2) and led to direct electron transfer from Co3O4 to N-doped TiO2 layer. The optical transmittance modulation ΔT = Tb− Tc was 27.1% after 2.5 h irradiation by xenon light
