Metamaterial solar absorber based on titanium resonators for operation in the ultraviolet to near-infrared region
Mojtaba Ehsanikachosang, Kianoosh Karimi, Mir Hamid Rezaei, Hamidreza Pourmajd
Abstract
In this work, we design an ultra-broadband metamaterial solar absorber with near-unity absorption. The absorber’s structure is optimized by using the particle swarm optimization algorithm. A unit cell of the absorber consists of three <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">T</mml:mi> <mml:mi mathvariant="normal">i</mml:mi> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">T</mml:mi> <mml:mi mathvariant="normal">i</mml:mi> <mml:mi mathvariant="normal">O</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">T</mml:mi> <mml:mi mathvariant="normal">i</mml:mi> </mml:mrow> </mml:math> square disks enclosed by a Ti square ring resonator, all superimposed on a thin stack of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">T</mml:mi> <mml:mi mathvariant="normal">i</mml:mi> <mml:mi mathvariant="normal">O</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">T</mml:mi> <mml:mi mathvariant="normal">i</mml:mi> </mml:mrow> </mml:math> films. The optimized structure shows high average absorption of 96.92% over the full wavelength range of 200–3200 nm. The over 90% absorption bandwidth is 3000 nm, which covers the ultraviolet, visible, and near-infrared regions. The solar absorption of the structure is 95.5% in the range of 280–3200 nm. The absorber is polarization independent and insensitive to incident angle changes. The absorption remains higher than 80% and 75% for TM and TE polarizations, respectively, even under oblique incidence radiation up to 55°. The structure possesses high thermal and chemical stability owing to the use of Ti and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">T</mml:mi> <mml:mi mathvariant="normal">i</mml:mi> <mml:mi mathvariant="normal">O</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> materials. Due to its outstanding features, the absorber has high potential to be used in solar energy harvesting, thermo-photovoltaics, and thermal emitting applications.