Magnetically Assembled Ultrablack Surface with Omnidirectional and Broadband Light Absorption

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Ultrablack surfaces are essential for advanced optical applications and solar-heat conversion.
• Existing ultrablack surfaces often struggle with stability, omnidirectional absorption, and wide spectral range performance.

Purpose of the Study:

• To develop a novel ultrablack surface with stable and omnidirectional light absorption.
• To investigate a nature-inspired needle-like array structure (NAS) for enhanced light absorption properties.

Main Methods:

• Fabrication of a needle-like array structure (NAS) using magnetic composite ink.
• Self-assembly of NAS under an external magnetic field.
• Characterization of optical properties, including hemispherical reflectance and angular dependence.

Main Results:

• Achieved extremely low hemispherical reflectance (≤0.3%) across a wide spectral range (300-2000 nm).
• Demonstrated stable omnidirectional absorption with insensitivity to incident angles up to 70°.
• Attributed performance to synergistic structural absorption and magnetic particle light scattering.

Conclusions:

• The NAS presents one of the darkest surfaces reported, with significant potential for optical and solar energy applications.
• The material exhibits excellent photothermal conversion, self-cleaning, flexibility, and thermal-aging resistance.
• Offers a promising alternative for constructing practical ultrablack surfaces.