Is there such a paint / pigment that absorbs most wavelengths of light (beyond the visible light range) that can be used for solar heat generating applications? If not, would it be possible to make it? Ideally, this paint would absorb light from the sun in an efficient manner and become heated quickly by solar light. It should probably at least absorb infrared, and any other wavelengths of light that produce significant heat when absorbed. This should be far more effective than normal black paint as black paint only "for sure" absorbs light in the visible spectrum, and this desired paint would absorb other types of light from the sun.
Carbon nanotube black is highly absorbent in and outside the visible spectrum, see http://www.extremetech.com/extreme/186229-its-like-staring-into-a-black-hole-worlds-darkest-material-will-be-used-to-make-very-stealthy-aircraft-better-telescopes.
Of course, that does not make it ideal for energy conversion, as it would also need at least the following qualities to be practical.
- A good conductor of heat to the heat-exchanger surface below
- An enduring finish, resistant to abrasion, heat and environmental degradation
- Economical, both in material cost and application
- Safety in use and in manufacture