Optimization design of Ti0.5Al0.5N/Ti0.25Al0.75N/AlN coating used for solar selective applications

A new solar selective coating was optimization designed in our paper. Ti0.5Al0.5N and Ti0.25Al0.75N coatings were chosen as absorber layers and AlN coating was chosen as anti-reflection layer. The phase structure and optical constants of these coatings were studied by X-ray diffraction and spectroscopic ellipsometry, respectively. The Ti0.5Al0.5N coating has a cubic NaCl-type structure and exhibits metallic character. However, the Ti0.25Al0.75N coating consists of cubic NaCl-type structure and hexagonal AlN structure and exhibits semiconducting property. AlN coating is expected as a dielectric layer. The solar selective coating was optimized using a computer program named TFCalc and verified by experimental results. The absorptance and low emittance of the optimized solar selective coating were 0.945 and 0.04 (82 °C), respectively.