Super Black Material Lifts The Bar for Solar Absorption Levels

New versions of earth’s blackest material has been created for the solar industry.
Published: Fri 02 Oct 2015

Scientists at a British nanoelectronics company, Surrey Nanosystems have developed a super-black material which absorbs a world record 99.96% of surface light. Only 0.04% will bounce back.  For comparison, fresh asphalt reflects 4% of the light that falls on it, and after a while this rises to 12%, while coal seldom gets below 0.5%.

The blackest material on earth

Vantablack is said to be so dark that it reduces 3D images into two dimensional planes, in fact, it is so dark that it is like looking into a black hole.  Vantablack is basically a forest of carbon nanotubes, 10,000 times thinner than a human hair, on an aluminium foil.

The Vanta in Vantablack stands for “vertically aligned carbon nanotube arrays”. The company is obviously guarding its manufacturing secrets but scientists think that there could be an ALD (atomic layer deposition) or CVD (chemical vapour deposition) carbon nanotubes on an aluminium substrate.

While closely packed vertically aligned carbon nanotubes absorb light (photons) they don’t let the photons exit. Basically, carbon nanotubes (like graphene) are incredibly absorbent to most forms of radiation — so incident radiation strikes the material, and then bounces around and gets absorbed so effectively that almost no radiation escapes. It’s for a similar reason that graphene is being looked at for ultra-sensitive imaging sensors.[ Graphene Demonstrates Benefits For Storage (And Other Technologies)

Vantablack is formed on an aluminium foil which makes it easy to create complex topography that is entirely invisible to the eye. The low-temperature nanotube growth processes give it a significant advantage past super-black materials that require high temperatures to produce, and are therefore incompatible with sensitive electronics.

Surrey NanoSystems doesn’t say which frequencies of radiation are absorbed, but previous studies show that carbon nanotubes are incredibly absorbent across a huge range of spectra, from ultraviolet, to visible light, to infrared, to microwaves. This makes Vantablack ideal for stealth aircraft, weapons, and a whole host of other military uses. It will also be used on the inside of telescopes and other imaging devices, where absorbing stray radiation can significantly reduce the amount of noise, thereby increasing the effective range and resolution. Vantablack’s first customers are in the defence and space sectors.

Two years ago, NASA developed a very similar material called super-black, but there’s been no word on whether the agency has successfully found a way of mass producing it. Currently, instead of super-black materials, the insides of telescopes are simply covered with very black paint (Aeroglaze Z306).

Black material-a  renewable incubator?

With the knowledge that this colour could well become a renewable incubator, Surrey Nanosystems has created a number of applications for a new version of Vantablack designed specifically for the solar spectrum.  

A modified version of the original material, Vantablack, the Vantablack S-VIS has been launched specifically for the energy industry. It’s reflectance in the UV-near infra-red is roughly 10 times better than the best commercial black paint absorbers available, and a lot better than physical vapour deposition (PVD) or Anodize absorbers . PVD has been around for decades primarily in military applications originally designed to decrease friction wear on metal parts. It bonds a micron thick layer of metal compounds to metal or other materials. It reduces reflective glare.

The product has yet to be launched but according to Chief Technical Officer Ben Jensen of Surrey Nanosystems, customers are already trialling it in their applications.