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With the development of new materials and technology, high entropy alloy (HEA) nitride films have attracted much attention of researchers due to their excellent optical properties and mechanical properties. Herein, a novel SS/NbMoTaWN (HEAN)/NbMoTaWON (HEAON)/SiO2 coatings are prepared, which shows a high spectral selectivity of α/ε = 0.944/0.12. The preparation and optimization of the coating are studied by combining experiments with ellipsometric program and CODE software. High temperature thermal stability test is performed in depth, which proves that the coating could bear 400 °C in air for 2 h, and 600 °C for 2 h in vacuum. Long-term thermal stability researches indicate that the SSACs still keep good optical properties (α = 0.902, ε = 0.106) even after annealing at 600 °C for 100 h. The failure mechanism is analyzed by XRD and Raman spectra. In addition, neutral salt spray test is performed to investigate the anti-corrosion ability, which indicates the coating has a good optical performance after soaking in 3.5 wt% NaCl solution for 30 days. Obviously, this work provides a new strategy to construct solar absorber coatings based on NbMoTaW high entropy alloy.

High entropy alloys (HEAs), which is at the expense of high cost compared to traditional alloy, should not be confined to the mechanical properties, but should be employed to devise a novel combination with unique functional and mechanical performances. In this work, high entropy alloy nitride (HEAN) is utilized as a novel double absorption layer to improve solar absorption in the high temperature solar selective absorbing coatings (SSACs). Our primary motivation is to lower thermal emittance (ε) and enhance solar absorptance (α). In order to realize this goal, coating design (CODE) software is employed to design and optimize the proposed HEAN based SSACs using appropriate dielectric function model. The ultimate as-deposited coating shows good optical properties with a high α value of 0.965 and a low ε value of 0.086 (at 82 °C). The estimate of thermal stability tests indicates that HEAN based SSACs has the ability to resist instability in high working temperature, which keeps good optical properties (α = 0.925, ε = 0.070) after annealing at 600 °C for 10 h.