Optimization of AlCrO-based absorber with Mo infrared reflector for solar selective applications

Preparation and optimization of AlCrO-based solar selective absorber is reported in this paper. The AlCrOx thin films were prepared on silicon and quartz substrates by cathodic arc ion plating. The chemical composition and structure of the thin films were measured by RBS, XRD and TEM. And the optical constants were obtained by modeling of the reflectance and transmittance spectra of the thin films on quartz substrates. A three-layered stack absorber was then designed using the optical constants. The effects of composition and thickness of individual layers in the stack on the reflectance spectra was systematically investigated, and an optimized absorptance of 0.942 was obtained. The optimized stack with Mo infrared reflective layer was deposited on silicon substrate, and very similar reflective behavior between the measured and simulated spectra was observed. The experimental absorptance and thermal emittance of the stack were 0.927 and 0.094, and the measured thicknesses by TEM of each layer were very close to the calculated thicknesses.