Blacker than black material

The perfect black body exists only in textbooks, a theoretically thermodynamic thought that suggests that all energy hitting the surface of such a body is absorbed and subsequently emitted with no energy lost. In reality, such an entity does not exist, but by taking inspiration from what seems to be the polar opposite, the whiter than white Cyphochilus beetle, researchers in Saudi Arabia have ripped a leaf from that textbook to make a material that is the blackest ever synthesised.


I explain in the magazine Chemistry World how Andrea Fratalocchi of the King Abdullah University of Science and Technology (KAUST) and colleagues suggest that their broadband light absorbing material could open up new approaches to energy-harvesting, optical and optoelectronic devices.

I asked Silvia Vignolini of the University of Cambridge for her thoughts on the research, as an expert on natural and biomimetic photonic structures. This is what she had to say:

Natural systems are a great inspiration for scientists, [the researchers] demonstrate how the Cyphochilus beetle taught us that a continuous interconnected network of scattering elements allows us to achieve an angular- and wavelength-independent response. This general concept can be applied for improving white as well black materials. However, nature is still ahead of us regarding optimization, when we compare results in a film-like geometry, natural materials outperform artificial structures in terms of density and weight, i.e. less material is needed to obtain similar performance. Some butterflies directly optimize darkness to regulate their body temperature, it would be interesting to have a one-to-one comparison of the structural and material effects to test how well we are doing in comparison with nature when designing the geometry of novel optical materials.

This area of research, biomimetic photonics, which aims to emulate the wonderful optical and visual properties of beetle exoskeletons, butterfly wings, the opalescent sheen of mother of pearl and many other natural materials, is growing steadily. Each iteration blurs the lines between what nature has had millions of years to achieve through evolution and what scientists can do in the laboratory. It is leading is along new avenues of fundamental research as well as opening technological doors for the kinds of systems, solar-energy conversion, optical computers, that will help us solve many of the problems we must face in the 21st Century.