Solar absorptance of copper-cobalt oxide thin film coatings with nano-size, grain-like morphology: Optimization and synchrotron radiation XPS studies

► We use sol-gel dip-coating to deposit copper-cobalt oxides on aluminium substrate. ► Nano-size, grain-like morphology is observed for copper-cobalt oxide coating. ► Electronic structure of metal oxides is analyzed using synchrotron radiation XPS. ► The effects of copper/cobalt concentration ratios and dip-speed are also investigated. ► The optimal copper-cobalt oxide coating exhibits α = 83.4%.