The influence of oxygen in TiAlOxNy on the optical properties of colored solar-absorbing coatings

► Titanium-aluminum nitro-oxide TiAlOxNy with different ratio of oxygen to nitrogen was studied. ► The refractive index of TiAlOxNy gradually decreases with increasing oxygen content. ► Solar absorptance increases by adding TiAlOxNy as middle layer while keeping color appearance. ► A gradient coating using the same target can be produced which will reduce cost.