Micro‐ and Nanostructured Surfaces for Selective Solar Absorption

Abstract

Applications utilizing solar energy are being actively developed due to increasing demand for environmentally friendly and sustainable energy solutions. The sun is a source of tremendous energy spanning from ultraviolet to infrared wavelengths, with the maximum energy in the visible range, corresponding to a blackbody temperature of 5780 K. [ 1 ] It is estimated that the amount of solar energy reaching Earth's surface is enough to Effi cient 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 fl exibility 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, fl exibility, and tunability is presented. Suggestions are also given regarding future research directions.

Highly efficient selective metamaterial absorber for high-temperature solar thermal energy harvesting

“…[27] So far, the optical and radiative properties of selective solar absorbers at elevated temperatures have been little experimentally studied. The state of the art of the micro/nanostructured selective solar absorber was recently reviewed by Khodasevych et al [28] In this work, we report on the spectroscopic characterization at both room and elevated temperatures of a selective metamaterial solar absorber made of a 2D titanium grating deposited on an MgF 2 spacer and an opaque tungsten film, as illustrated in Figure 1a. Tungsten is chosen as the substrate material due to its excellent high-temperature stability, while titanium is selected for the gratings as it is easier to pattern with lift-off process than tungsten.…”

Numerical study of a wide-angle polarization-independent ultra-broadband efficient selective metamaterial absorber for near-ideal solar thermal energy conversion

“…The average absorption can reach as high as 98.95% over the wavelength range of 260 to 1580 nm, which signicantly exceed most of previously reported metamaterial solar absorbers both in the efficiency and bandwidth of solar absorption. 6,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] The proposed solar absorber are numerically demonstrated to possess a near perfect absorption in the UV region from 250 to 400 nm. At the same time, the mid-infrared absorption is decreased signicantly, which is remarkably benecial for the improvement of the total photothermal conversion efficiency.…”

“…Thus, similar to the conclusion in the ref. 6, it is a meaningful but challenging work to achieve a wide-angle, polarization independent, ultra-broadband, nearperfect and selective absorption covering the whole solar spectrum using plasmonic metamaterials, especially based on a relatively simple structure.…”

“…In order to maximize the total photothermal conversion efficiency of solar absorbers, the spectrally selective absorption is very essential, which means that the solar absorber possesses an efficient solar absorption and simultaneously suppresses mid-infrared emission. 6 Therefore, the study of near-ideal solar absorbers is of fundamental importance for many promising applications, and the improvement in the performance of solar absorbers would greatly promote the solar-thermal industry. Unfortunately, the design of these solar absorbers with strong spectral selectivity, near-perfect solar absorption, angular independence and polarization independence are still difficult.…”

Toward Highly Efficient Nanostructured Solar Cells Using Concurrent Electrical and Optical Design

“…[16][17][18][19][20][21][22][23][24] These authors point out that important work remains to ensure that improved optical absorption does not come at the sacrifice of the device's electrical properties. [16,17,[19][20][21][22][23][24] However, there have been few reviews that propose a solution for how to overcome this challenge.…”