Highly Enhanced Thermal Robustness and Photothermal Conversion Efficiency of Solar-Selective Absorbers Enabled by High-Entropy Alloy Nitride MoTaTiCrN Nanofilms

Area of Science:

• Materials Science
• Nanotechnology
• Renewable Energy

Background:

• Solar-selective absorbers (SSAs) are crucial for photothermal conversion efficiency but suffer from thermal instability.
• High-entropy materials, like nitrides, present a promising solution to enhance SSA performance and durability.

Purpose of the Study:

• To develop a highly efficient and thermally stable solar-selective absorber using a high-entropy alloy nitride.
• To optimize the preparation parameters and investigate the properties of the MoTaTiCrN absorption layer for photothermal applications.

Main Methods:

• Utilized computational and experimental approaches to determine optimal thicknesses and constituents for the MoTaTiCrN layer.
• Investigated the crystal structure, including thickness-dependent crystal nucleation, of the high-entropy ceramic.
• Conducted high-temperature and long-term thermal stability tests to assess mechanical robustness and chemical stability.

Main Results:

• Achieved exceptional thermotolerance and optical properties with the MoTaTiCrN absorption layer.
• Demonstrated mechanical robustness and chemical stability through rigorous thermal testing.
• Reported low thermal emittance (15.86% at 500 °C), high spectral selectivity (α/ε = 92.3/6.5%), and excellent photothermal conversion efficiency (86.9% at 550 °C under 100 sun).

Conclusions:

• The developed high-entropy ceramic MoTaTiCrN SSA exhibits superior spectral selectivity and thermal stability.
• This scalable, cost-effective SSA structure significantly enhances the practical realization of large-area photothermal conversion, particularly for concentrated solar power systems.