Multilayer films for coloured glazed solar collectors

In this work a solution to the problem of black colour appearance which dominates the external aspect of buildings covered by solar thermal collectors is proposed.
Multilayered thin films on the glass surface, consisting of oxides materials such as SiO2, Al2O3, TiO2 or a mixture of these oxides were deposited by reactive magnetron sputtering on glass and their optical properties were examined.
As the interface between the sputtered layers on glass emerged as important, the interfaces formed between TiO2 and SiO2 and between Al2O3 and SiO2 were studied by X-ray photoelectron spectroscopy.
The reflectivity of the film on glass system was shown to be a narrow band in the visible region while the rest of the sunlight is transmitted through the glass due to the use of a near zero absorption materials.
In addition, the desired colour of the reflected light in the visible range was obtained by adapting the oxide film thicknesses.
Such optical properties besides the film’s stability as demonstrated in accelerated ageing tests make the coloured glazing aesthetically pleasing and suitable as a cover glass for thermal solar collectors.