What's The Darkest Material On Earth?

From Popular Science - New Technology, Science News, The Future Now:

The idea of dark materials might sound familiar to you if you read fantasy trilogies or like casually memorizing lines from Paradise Lost. Unfortunately, this material isn't used to create more worlds--but it might help save this one. Vertically aligned carbon nanotubes (VACNT), the darkest material known to man, was developed by researchers at Rennselaer Polytechnic Institute (RPI) in 2007. With the ability to absorb 99.970 percent of light, VACNT has significant implications in solar energy research. For instance, it can be used to improve the efficiency of solar panels. Rennselaer's researchers aren't the only ones attempting to produce ultra-dark materials. They've been in a quasi-competition with NASA, which developed a material also made of carbon nanotubes and created using the same process. But at only 99.5 percent absorption, it is not quite as dark as Rennselaer's VACNT.