Efficient absorption of solar radiation is desired for the renewable energy sector, such as solar thermophotovoltaics and solar thermal applications. In order to minimize thermal re-radiation, wavelength-selective devices are required. Absorbers with structured surfaces are attractive because they derive their electromagnetic properties to a greater extent from their geometry and to a lesser extent from the intrinsic properties of the constituent materials. Thus, they offer greater flexibility in the design and control of absorber features and can be tailored to suit requirements. This article reviews various classes of patterned structures: photonic crystals, metal-dielectric-metal slab arrays, metamaterials, and nanostructures operating in the visible and infrared wavelength ranges. Operation requirements, design principles and underlying physical phenomena, material and temperature considerations, as well as fabrication methods are discussed. Recent progress in achieving various desirable absorber features, such as broadband and multiband operation, polarization and angle independence, flexibility, and tunability is presented. Suggestions are also given regarding future research directions.
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