Reconfigurable and optically transparent microwave absorbers based on deep eutectic solvent-gated graphene.

Area of Science:

• Materials Science
• Electrical Engineering
• Applied Physics

Background:

• Graphene's unique electronic properties make it suitable for tunable microwave devices.
• Controlling graphene's electrical characteristics for reconfigurable surfaces remains a challenge.

Purpose of the Study:

• To design and fabricate electrolytically tunable graphene building blocks.
• To explore Deep Eutectic Solvents (DESs) for tuning graphene's microwave response.
• To investigate reconfigurable microwave surfaces and absorbers.

Main Methods:

• Fabrication of graphene building blocks.
• Utilizing Deep Eutectic Solvents (DESs) as electrolytic media.
• Electrolytic tuning of graphene's sheet resistance and Fermi level.
• Characterization of microwave response (reflection, transmission, absorption) using numerical simulations and experimental measurements.

Main Results:

• Demonstrated electrolytic tunability of graphene's microwave response using DESs.
• Achieved control over transmittance, absorption, and reflectance in X and Ku bands.
• Showcased near-perfect absorption (approx. 20% modulation) in a Salisbury screen absorber configuration.
• Validated tunability by varying gate voltage between -1.4/+1.4 V.

Conclusions:

• DESs provide an effective and environmentally friendly medium for tuning graphene's microwave properties.
• The developed graphene building blocks enable reconfigurable and optically transparent microwave surfaces and absorbers.
• Potential applications include electromagnetic pollution control, microwave cloaking, and advanced optical devices.