Transparent grating-based metamaterials for dynamic infrared radiative regulation smart windows

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Dynamic infrared radiation regulation is crucial for smart windows, impacting building comfort and energy efficiency.
• Achieving both high visible transmittance and significant infrared tunability simultaneously remains a challenge.

Purpose of the Study:

• To propose and demonstrate a dynamic infrared tunable metamaterial for advanced smart window applications.
• To overcome the limitations of current smart window technologies in balancing visible transmittance and infrared control.

Main Methods:

• Fabrication of a metamaterial structure using indium tin oxide (ITO) gratings, an air insulator, and an ITO reflector.
• Characterization of the infrared emissivity and visible transmittance properties before and after actuation.
• Investigation of the underlying physical mechanisms, including Fabry-Pérot and surface plasmon resonance effects.

Main Results:

• The proposed ITO grating metamaterial achieved high emissivity tunability (0.73) in the 8-13 μm range.
• High visible transmittance was maintained (0.65 before, 0.72 after actuation).
• Ultra-broadband tunability (0.62) was achieved by extending the tunable bandwidth to 3-30 μm through geometric parameter adjustments.

Conclusions:

• The developed metamaterial demonstrates excellent infrared tunable performance due to tunable resonance coupling.
• This technology holds significant potential for advancing smart window applications and contributing to sustainable building design.