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Fabrication of High Contrast Gratings for the Spectrum Splitting Dispersive Element in a Concentrated Photovoltaic System
Published on: July 18, 2015
High performance solar-selective absorbers using coated sub-wavelength gratings.
Nicholas P Sergeant1, Mukul Agrawal, Peter Peumans
1Dept. of Electrical Engineering, Stanford University, Stanford, CA 94305 USA.
Optics Express
|April 15, 2010
Summary
Researchers designed novel V-groove gratings coated with metal-dielectric stacks to control surface emissivity. These structures show potential for highly efficient solar thermal energy conversion by minimizing heat loss.
Area of Science:
- Nanophotonics and Plasmonics
- Materials Science and Engineering
- Renewable Energy Technologies
Background:
- Efficient solar thermal energy conversion requires precise control over surface emissivity.
- Existing technologies face limitations in spectral selectivity and angular performance.
Purpose of the Study:
- To investigate sub-wavelength V-groove gratings coated with aperiodic metal-dielectric stacks for spectral emissivity control.
- To enhance the efficiency of concentrated solar thermal systems through optimized surface properties.
Main Methods:
- Rigorous coupled-wave analysis (RCWA) was employed to model the spectral behavior of the coated gratings.
- The design incorporates impedance matching with tapered metallic features and selective spectral properties of metal-dielectric stacks.
- V-groove aspect ratio was optimized for spectral selectivity across a wide angular range.
Main Results:
- Optimized coated V-groove gratings demonstrated predicted thermal emissivity below 6% at 720K.
- These surfaces achieved >94% absorption of incident light.
- The tailored spectral selectivity was maintained over a broad angular range.
Conclusions:
- The developed sub-wavelength gratings offer significant potential for improving the efficiency of concentrated solar thermal systems.
- Spectral control of emissivity using these nanostructured surfaces is a promising approach for advanced solar energy harvesting.
