Ultra-Broadband Solar Absorption Enabled by 3D Crown-like Aluminum Nanostructure Arrays

Area of Science:

• Materials Science
• Nanotechnology
• Renewable Energy

Background:

• Plasmonic nanostructures are promising for solar-to-thermal conversion.
• Challenges include achieving broadband absorption, scalability, and stability with earth-abundant materials like aluminum.

Purpose of the Study:

• To develop a 3D crown-like aluminum nanostructure absorber for efficient and stable solar-to-thermal conversion.
• To demonstrate a scalable fabrication method for large-area production.

Main Methods:

• Fabrication of 3D crown-like aluminum nanostructures using anodic aluminum oxide (AAO) templates.
• Characterization of optical absorption across the solar spectrum (200-2500 nm).
• Long-term stability testing over 24 months and electromagnetic simulations.

Main Results:

• Achieved an average solar absorption of 92% with only 1.9% degradation over 24 months.
• Demonstrated scalable, lithography-free fabrication with broad tolerance to deposition variations.
• Identified synergistic absorption mechanisms: multi-mode electric and magnetic resonances, and graded refractive index.

Conclusions:

• The developed aluminum nanostructure absorber is scalable, durable, and cost-effective for ultra-broadband solar absorption.
• Presents a viable design strategy for plasmonic absorbers using earth-abundant materials.
• Confirms enhanced solar-to-thermal energy utilization through photothermal experiments.