High-Performance Spectrally Selective Absorber Using the ZrB₂-Based All-Ceramic Coatings

Enhancing the spectral selectivity and thermal stability of the absorber used in the concentrated solar power system would boom the conversion efficiency of solar energy to electricity. The ceramic coatings possess excellent thermal stability in optical films. Here, we design the ZrB2-based all-ceramic spectrally selective absorber with a quasioptical microcavity (QOM) structure, which shows an excellent performance with a solar absorptance of 0.965 and superior thermal stability. The pretty high absorptance is due to the design of QOM inducing the multiabsorption mechanisms composed of the intrinsic cermet absorption, the surface plasmon polaritons, and localized surface plasmon resonance proved by the electromagnetic power loss. The structure also demonstrates well-matched impedance with free space in the solar spectrum range, ensuring a high solar absorptance. The proposed absorber can survive at 800 °C in vacuum or 500 °C in air for 200 h, ascribed to the introduction of QOM and ultrahigh-temperature ceramic ZrB2. The total conversion efficiency of an ideal system with this absorber and an ideal thermal engineer can reach around 67% under the conditions of 800 °C and 1000 suns.