Unraveling the optoelectronic properties of CoSbx intrinsic selective solar absorber towards high-temperature surfaces

Abstract

The combination of the ability to absorb most of the solar radiation and simultaneously suppress infrared re-radiation allows selective solar absorbers (SSAs) to maximize solar energy to heat conversion, which is critical to several advanced applications. The intrinsic spectral selective materials are rare in nature and only a few demonstrated complete solar absorption. Typically, intrinsic materials exhibit high performances when integrated into complex multilayered solar absorber systems due to their limited spectral selectivity and solar absorption. In this study, we propose CoSbx (2 < x < 3) as a new exceptionally efficient SSA. Here we demonstrate that the low bandgap nature of CoSbx endows broadband solar absorption (0.96) over the solar spectral range and simultaneous low emissivity (0.18) in the mid-infrared region, resulting in a remarkable intrinsic spectral solar selectivity of 5.3. Under 1 sun illumination, the heat concentrates on the surface of the CoSbx thin film, and an impressive temperature of 101.7 °C is reached, demonstrating the highest value among reported intrinsic SSAs. Furthermore, the CoSbx was tested for solar water evaporation achieving an evaporation rate of 1.4 kg m−2 h−1. This study could expand the use of narrow bandgap semiconductors as efficient intrinsic SSAs with high surface temperatures in solar applications.

Surface Reconstruction of La0.5Sr0.5CoO3-δ Ceramic toward High Solar Selectivity for High-Temperature Air-Stable Solar–Thermal Conversion

“…14,15 In recent years, many efforts focused on solar absorbers have been made to enhance the efficiency of CSP systems. 16,17 Spectrally selective absorption coatings (SSACs) were employed as solar absorbers, 18,19 such as cermets (e.g., TiC/ TiN-Ni/Mo 20 and WTi-Al 2 O 3 21 ), semiconductor−metal tandems (e.g., Ti/TaC/Al 2 O 3 22 and Cr 2 O 3 /Cr/Cr 2 O 3 23 ), photonic crystals (e.g., HfO 2 /Al 2 O 3 24 and HfO 2 /Ta 25 ), and multiple metal/ceramic nanofilms (e.g., CuCo 2 O 4 /W/ CuCo 2 O 4 26 and Ti/SiO 2 /Cu 27 ). The spectrum selectivity of the SSACs could be enhanced by designing ingenious structures.…”