Bioinspired Structured Metal-Insulator-Metal Metamaterials with Gradient Resonator for High Efficiency and Solar...

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Efficient solar energy utilization is critical for sustainable energy solutions.
• Metal-insulator-metal (MIM) absorbers offer high solar absorption and low thermal emission.
• Traditional planar MIM absorbers suffer from narrow absorption bands and limited spectral tunability.

Purpose of the Study:

• To design and fabricate a structured MIM metamaterial (SMM) for omnidirectional and polarization-insensitive selective solar absorption.
• To overcome the limitations of traditional planar MIM absorbers in spectral tuning and absorption bandwidth.
• To enhance photothermal conversion efficiency for solar energy applications.

Main Methods:

• Fabrication of a concave-structured MIM metamaterial with gradient resonance cavities.
• Characterization of optical properties, including absorptivity and emissivity.
• Evaluation of photothermal conversion performance under concentrated solar illumination.

Main Results:

• The SMM absorber achieved 91% absorptivity across the 0.3-2.5 µm solar spectrum.
• Infrared emissivity was maintained at a low value of 0.09.
• The SMM absorber demonstrated stable photothermal conversion, reaching 165 °C under 3 sun illumination.
• The structured design exhibited size insensitivity, simplifying practical applications.

Conclusions:

• The novel SMM design significantly enhances solar absorption bandwidth and spectral selectivity compared to planar MIM structures.
• The SMM absorber provides an effective approach for efficient solar-to-thermal energy conversion.
• This structured metamaterial offers a promising pathway for advanced solar selective absorber applications.