Semiconductor-dielectric-metal solar absorbers with high spectral selectivity
Journal Article
·
· Solar Energy Materials and Solar Cells
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
An ideal solar thermal absorber has a sharp transition between high and low absorptance at the wavelength where the blackbody emissive power begins to exceed the solar irradiance. However, most real selective absorbers have a fairly broad transition, leading to both solar absorption and thermal emission losses. Here, we model, fabricate, and characterize a highly selective semiconductor-dielectric-metal (Ga0.46In0.54As - MgF2 - Ag) solar absorber with an extremely sharp transition from high to low absorptance. The thin semiconductor serves as a selective filter, absorbing photons with wavelengths shorter than the bandgap and transmitting those with longer wavelengths. The highly reflective dielectric-metal rear mirror allows the structure to have very low emittance for longer wavelengths. These characteristics provide the absorber with a measured solar absorptance >91% below the bandgap wavelength and infrared emittance <5% at 100 degrees C above the bandgap wavelength. This transition wavelength can be tuned by modifying the semiconductor composition, and modeling indicates that the absorber's optical properties should be stable at high temperatures, making the structure a good candidate for unconcentrated to highly concentrated solar thermal energy conversion.
- Research Organization:
- National Renewable Energy Laboratory (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE; USDOE National Renewable Energy Laboratory (NREL), Laboratory Directed Research and Development (LDRD) Program
- Grant/Contract Number:
- AC36-08GO28308
- OSTI ID:
- 1863213
- Alternate ID(s):
- OSTI ID: 1862491
- Report Number(s):
- NREL/JA-5900-81677; MainId:82450; UUID:7b2ebcba-f549-4e73-b984-1e0c5520a267; MainAdminID:64276
- Journal Information:
- Solar Energy Materials and Solar Cells, Journal Name: Solar Energy Materials and Solar Cells Vol. 240; ISSN 0927-0248
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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