Experimental Observation of an Extremely Dark Material Made By a Low-Density Nanotube Array

Abstract

An ideal black material absorbs light perfectly at all angles and over all wavelengths. Here, we show that low-density vertically aligned carbon nanotube arrays can be engineered to have an extremely low index of refraction, as predicted recently by theory [Garcia-Vidal, F. J.; Pitarke, J. M.; Pendry, J. B. Phys. Rev. Lett. 1997, 78, 4289-4292] and, combined with the nanoscale surface roughness of the arrays, can produce a near-perfect optical absorption material. An ultralow diffused reflectance of 1 x 10(-7) measured from such arrays is an order-of-magnitude lower compared to commercial low-reflectance standard carbon. The corresponding integrated total reflectance of 0.045% from the nanotube arrays is three times lower than the lowest-ever reported values of optical reflectance from any material, making it the darkest man-made material ever.

Large Photonic Strength of Highly Tunable Resonant Nanowire Materials

“…6 Nanowires exhibit novel properties of interest for applications in light emission, 1 biosensing, 7 and next-generation solar cells. [2][3][4][5] Light scattering is inherent to many nanostructured materials and holds promise for new approaches to light management in thinfilm devices.…”

Visible iridescence from self-assembled periodic rippling in vertically aligned carbon nanotube forests

“…For example, Yang et al 1 report that nanotube forests are among the blackest known materials when observed along the axes of the nanotubes. However, at other angles of incidence, nanotube forests are noticeably reflective, particularly from their sidewalls.…”

Near-perfect 'black'

“…But he says that making a perfect black in the visible range will be hard, because the components would have to be so small. A super-black material made from carbon nanotubes was reported recently 4 , in which the high absorbance comes from the roughness of the surface rather than the antenna action of metamaterials.…”