Scalable and Ultrathin High‐Temperature Solar Selective Absorbing Coatings Based on the High‐Entropy Nanoceramic AlCrWTaNbTiN with High Photothermal Conversion Efficiency

Abstract

High‐entropy ceramics, especially high‐entropy alloy nitrides (HEANs), have attracted increasing attention in recent years due to their unique structural characteristics that result in their potential use in correlated high‐temperature structural materials. However, research on their optical properties, especially the spectral selectivity, is still in its infancy. According to Carnot efficiency, which demands an extremely high working temperature to elevate the performance of a concentrating solar power (CSP) system, excellent thermal stability is valuable to meet the requirements of solar selective absorbing coatings (SSACs). Herein, the high‐entropy ceramic AlCrWTaNbTiN is introduced as effective absorption layers by adjusting the nitrogen content to design and fabricate an ultrathin multilayer solar absorbing coating, which exhibits a high solar absorptance of 93% and a low emittance of 6.8% at 82 °C. Coating design (CODE) software is used to design and optimize the multilayer solar absorbing coating. Moreover, the optical properties, microstructure, thermal stability, and failure mechanism are investigated. Finite‐difference time‐domain (FDTD) calculations are used to understand the nature of the optical absorption consisting of intrinsic absorption and extinction absorption.

Solar Selective Absorber for Emerging Sustainable Applications

“…Alloy composed of five or more main elements is called high entropy alloys (HEAs), which is emerging as a new promising SSA material. It was reported that HEA containing transition metal elements (such as Ti, Ta, Hf, Mo, Cr, and Zr) have excellent thermodynamic and optical properties, such as AlCrTaTiZrN, [ 30 ] (AlCrTaTiZrRu)N 0.7 , [ 31 ] Al 0.4 Hf 0.6 NbTaTiZrN, [ 32 ] AlCrWTaNbTiN, [ 33 ] etc. These have been widely studied because of their excellent thermal stability.…”

Boosting Total Conversion Efficiency of Hybrid Photovoltaic–Thermal via a Spectral Splitter/Absorber Based on Lossy Periodic Structured Media

“…[4][5][6][7][8] Photothermal (PT) and photovoltaic (PV) are two primary technologies for harvesting sunlight and converting it into useable energy. [9][10][11][12][13][14][15] As shown in Figure 1a, PT and PV have different spectral efficiencies. For an ideal PT absorber, the spectral efficiency is wavelength independent and the entire solar spectrum (280-2000 nm) can be effectively harvested.…”

Uninterrupted Self‐Generation Thermoelectric Power Device Based on the Radiative Cooling Emitter and Solar Selective Absorber

“…It can run stably under the environment. He et al [25] adjusted the nitrogen content of the high-entropy ceramic AlCrWTaNbTiN to design and fabricate an ultrathin multilayer solar absorbing coating, which exhibits a high solar absorptance of 93% and a low emittance of 6.8% at 82 C. Under the irradiation of simulated sunlight, they obtained the surface temperature of 105 C by a TiVCrAlZr layer with gradient high-entropy nitride nanofilms. [26] Wu et al [27] proposed to replace the pure dielectric layer of the laminated interference coating with a cermet coating film to prepare a composite structure of W/W-SiO 2 /W/W-SiO 2 /Al 2 O 3 / SiO 2 .…”

“…It can run stably under the environment. He et al [ 25 ] adjusted the nitrogen content of the high‐entropy ceramic AlCrWTaNbTiN to design and fabricate an ultrathin multilayer solar absorbing coating, which exhibits a high solar absorptance of 93% and a low emittance of 6.8% at 82 °C. Under the irradiation of simulated sunlight, they obtained the surface temperature of 105 °C by a TiVCrAlZr layer with gradient high‐entropy nitride nanofilms.…”