Abstract
A full-spectrum near-unity solar absorber has attracted substantial attention in recent years, and exhibited broad application prospects in solar thermal energy conversion. In this paper, an all-metal titanium (Ti) pyramid structured metamaterial absorber (MMA) is proposed to achieve broadband absorption from the near-infrared to ultraviolet, exhibiting efficient solar-selective absorption. The simulation results show that the average absorption rate in the wavelength range of 200–2620 nm reached more than 98.68%, and the solar irradiation absorption efficiency in the entire solar spectrum reached 98.27%. The photothermal conversion efficiency (PTCE) reached 95.88% in the entire solar spectrum at a temperature of 700 °C. In addition, the strong and broadband absorption of the MMA are due to the strong absorption of local surface plasmon polariton (LSPP), coupled results of multiple plasmons and the strong loss of the refractory titanium material itself. Additionally, the analysis of the results show that the MMA has wide-angle incidence and polarization insensitivity, and has a great processing accuracy tolerance. This broadband MMA paves the way for selective high-temperature photothermal conversion devices for solar energy harvesting and seawater desalination applications.
Highlights
2008 [1], metamaterial absorber (MMA) has spurred the interest of many researchers due to its extensive application value, e.g., solar–thermal conversion [2,3,4], photovoltaic [5], plasmonic sensors [6,7,8], imaging [9,10], stray light elimination [11], thermal emitter [12,13,14,15], photodetectors [16], and so on
The nano-hole array was first obtained by nano-lithography technology, the pyramid hole model was obtained by nano-etching technology, and the pyramid array was obtained by electrochemical deposition
We study the effect of different oblique incidence angles on the absorption performance of the MMA under transverse electric (TE) and transverse magnetic (TM) polarizations, and the results are shown in Figure 7a,b, respectively
Summary
Since Landy et al first experimentally demonstrated metamaterial absorbers (MMA) in. 2008 [1], MMA has spurred the interest of many researchers due to its extensive application value, e.g., solar–thermal conversion [2,3,4], photovoltaic [5], plasmonic sensors [6,7,8], imaging [9,10], stray light elimination [11], thermal emitter [12,13,14,15], photodetectors [16], and so on. Lei and co-workers proposed a plasmonic metamaterial absorber composed of titanium-silica (Ti-SiO2 ) cubes and an aluminum (Al)-bottom film to obtain broadband absorption from visible light to near-infrared [30]. Despite the significant development of the above method in high-efficiency broadband absorption, it is still challenging to achieve ultra-broadband absorption of metamaterial absorbers with a simple structure, low processing cost, and simple experimental processing procedures for practical applications. Wu et al designed a nanoporous hyperbolic metamaterial structure to achieve high-efficiency solar absorption with an average absorption rate of more than 96% in the wavelength range of 250–1560 nm, and, at the same time, the light-to-heat conversion efficiency reached. The MMA has a simple and consistent structure and only one material used for processing, which greatly simplifies the processing flow and saves processing costs
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