Rice University carbon nanotube device channels heat into light

Non-paywalled version:

Macroscopically Aligned Carbon Nanotubes as a Refractory Platform for Hyperbolic Thermal Emitters

Weilu Gao, Chloe F. Doiron, Xinwei Li, Junichiro Kono, Gururaj V. Naik

https://arxiv.org/abs/1903.06063

Solar cells have a band gap energy which corresponds to a specific frequency of light. Photons below that frequency don’t knock any electrons loose (they just make heat) and photons above that frequency still only knock one electron loose (and the rest of the energy goes to heat). So a single band gap cell is limited to 20-something % max efficiency as a theoretical limit. The ability to re-emit heat at a specific frequency (that could be fed into a cell tuned for that frequency) would be really neat.

MWIR. 4um-ish.

The blackbody temp's they are using (>700C) center around 3um so it's also emitting peaks at lower energy. A graph overlaying the two is prob in the paper but so far I'm not seeing it.