Cross-Shaped Titanium Resonators Based Metasurface for Ultra-Broadband Solar Absorption

Jin Zhou,Zhengqi Liu,Junqiao Wang,Xiaoshan Liu,Mulin Liu,Qing Yi,Houjiao Zhang

doi:10.1109/jphot.2021.3052990

Abstract

We propose a scheme for ultra-broadband and polarization-insensitive metamaterial perfect absorber (PA) by utilizing a thin metal-insulator-metal (MIM) stack, which is comprised of an array of cross-shaped titanium resonators, a silica dielectric spacer, and an opaque titanium slab. The bandwidth of absorption (A) > 90% is up to 2100 nm, ranging from the visible to near infrared region. At the wavelength range of 400-2500 nm, this metamaterial absorber shows strong absorption of electromagnetic waves. The spectral average absorptivity reaches 93.8% and the maximal absorptivity is up to 99.8%. In addition, the simulations show that the absorption remains high over a broad range of incident angles. Additionally, we have investigated the influences of geometries, structural parameters and material features on the absorption properties. The utilization of titanium rather than the noble metals efficiently lowers the fabrication cost and enhances the thermal stability and biocompatibility, thus paving a way to numerous applications such as solar energy harvesting, imaging, infrared detection and bio-medical techniques.

Highlights

Metamaterials have long been investigated for their novel and tunable electromagnetic properties
Numerous metamaterial perfect absorber (PA) have been proposed and fabricated, and a series of valuable performances have been achieved such as the ultra-narrowband absorption [2], efficient hot electron generation [3], tunable response [4], and high-efficiency solar energy conversion [5]
Metamaterial PAs were usually based on the coinage-metals due to their remarkable plasmonic properties

Summary

Introduction

Metamaterials have long been investigated for their novel and tunable electromagnetic properties. To ensure the demand for broadband absorption and overcome the challenge of high operating temperatures, large amounts of efforts have been made to fabricate broadband metamaterial PAs with enhanced thermal robustness Refractory metals such as titanium, tungsten, nickel, and chromium have been utilized to construct high-temperature-resistant absorbers [6], [14]. Liu et al proposed a metamaterial solar absorber based on refractory metals via simulation methods [14] In this design, alternating metallic discs and silica discs are utilized to construct the electromagnetic resonators. Wang et al experimentally demonstrated an efficient broadband absorber based on titanium nanostructures and validated its potential for high-temperature solar energy harvesting applications [19]. The ultra-broadband and high-efficiency absorption can be attributed to the combination of surface plasmon resonances, Fabry-Pérot cavity resonance, and the intrinsic optical absorption properties of titanium

Geometric Parameters and Simulation Methods

Findings

Conclusion