Tuning the transmittance and the electrochromic behavior of CoxSiyOz thin films prepared by magnetron sputtering at glancing angle

•Porous CoxSiyOz thin films are prepared by magnetron sputtering.•Porous CoxSiyOz thin films are obtained by deposition at glancing angles.•The porous films present an outstanding electrochromic behavior.•The refractive index and color changes of the films are tuned by adjusting the Co/Si ratio.

This work reports the synthesis and the characterization of amorphous CoxSiyOz thin films prepared by magnetron sputtering from a single cathode. Porous layers with outstanding electrochromic properties are obtained at room temperature in one step by performing the deposition at a glancing angle configuration. The electrochromic behavior of these layers in a basic aqueous medium was dependent on the Co/Si ratio in the films and in all cases was characterized by a fast response, a high coloration efficiency and a complete reversibility after several hundred cycles. A characteristic feature of these electrochromic layers is that, for a similar thickness, the range of transmittance modulation can be tuned by changing the Co/Si ratio in the films and, specifically for films with a high concentration of silicon, to change their aspect from an almost transparent to a full colored state.

Graphical abstractThe range of the transmittance change achieved by electrochemically cycling cobalt and silicon mixed oxides is selected by controlling the Co/Si ratio in thin films prepared by magnetron sputtering at glancing angles.Figure optionsDownload full-size imageDownload as PowerPoint slide