LAUSR

Abstract Spectral control of light for efficient absorption and emission in the targeted wavelength region attracted considerable attention in recent years to attain high photothermal conversion efficiency. In this connection, a highly selective tandem absorber with wide-angular absorptance has been developed in the configuration of low emissive metallic layer by sputtering, absorber and anti-reflective layers by simple wet-chemical methods. The developed tandem absorber has a highly reflective Molybdenum (Mo) layer over on the glass substrate with emittance (e) of 0.04 and tri-transition metal precursors-based absorber on Mo layer to improve the solar absorptance. The coatings are annealed in a vacuum environment and the resultant nanocomposite absorber coating enhanced the solar absorptance from 0.36 to 0.90. The SiO2 nanoparticles-based anti-reflective layer over on nanocomposite absorber has been developed to enhance the optical properties and the final configured tandem absorber exhibited absorptance of 0.96, the emittance of 0.12 and selectivity of 8. The tandem absorber has also exhibited a good wide-angular absorptance with a net improvement of 3.7–10.8% from an angle of incidence 10–70° respectively. Hence, the developed tandem absorber may aid in achieving high photothermal conversion efficiency for solar thermal applications.