Growth and characterization of spectrally selective Cr2O3/Cr/Cr2O3 multilayered solar absorber by e-beam evaporation

Spectrally selective solar absorbers based on Cr2O3/Cr/Cr2O3 multilayered coatings were deposited onto stainless steel substrates by using an electron beam physical vapor deposition technique. The structural investigations of the multilayered coatings showed crystalline phase of Cr2O3 after annealing the coatings at 500 °C in air for 2 h. The Raman analysis revealed vibrational modes corresponding to Eg and A1g symmetries in Cr2O3. The gradual appearance of absorption bands associated with of CrO bond stretching was also observed from the attenuated total reflectance measurement. The Morphology investigations of the coatings by SEM showed presence of nanoparticles with size ranging from 40 to 50 nm in diameter. The AFM also revealed a columnar growth with an average surface roughness of 16 nm. The optical analysis of the coatings showed a combination of good solar absorptance of 0.89 and low thermal emittance of 0.25 at 100 °C. These optical properties could arise from a combination of interference, and intrinsic effects that occur in the multilayered solar absorber structure. These results indicate that a Cr2O3/Cr/Cr2O3 multilayered coating deposited by e-beam evaporation is an excellent thin films material for selective solar absorbers application.