High-Entropy Oxide Solar Selective Absorber

Sputter-deposited high-entropy materials, including high-entropy alloy (HEA) and high-entropy oxide (HEO), are demonstrated for use as selective solar absorber coatings (SSCs). Multi-layer SSC consists of CrFeCoNiAl HEA as the IR reflector layer, (CrFeCoNi)O medium-entropy oxide as the first layer absorber, and (CrMnFeCoNi)O HEO as the second layer absorber. The effects of phase and elemental concentration of the second layer absorber on the optical properties and thermal stability are addressed. The (CrMnFeCoNi)O HEO hematite has better spectral selectivity than the (CrMnFeCoNi)O HEO spinel. Meanwhile, from the X-Ray diffraction and transmission electron microscopy analyses of the annealed samples, the (CrMnFeCoNi)O HEO spinel exhibits better thermal stability than (CrMnFeCoNi)O HEO hematite. This work provides guidance to create an effective solar absorber.

(CrMnFeCoNi)O hematite solar absorber exhibits better spectral selectivity than (CrMnFeCoNi)O spinel. (CrMnFeCoNi)O spinel exhibits better thermal stability than (CrMnFeCoNi)O hematite. The thermal instability of the spinel originates from the metal diffusion.