Photovoltaic effect in ideal carbon nanotube diodes

Ji Ung Lee, "Photovoltaic effect in ideal carbon nanotube diodes"
Appl Phys Lett 87, 073101 (2005)

An experimental demonstration that individual single-wall carbon nanotubes can form IDEAL p-n junction diodes, and as a result, perform well as photovoltaic devices. Lee estimates that the efficiency is greater than 5% of light absorption
(the experimentally measured value is less, due to only a small amount of the light being absorbed for various
experimental reasons. The best part is that 0.8 nm diameter SWNTs have a band gap of 1.4 eV, which is almost ideal for for a single bulk junction device at the standard solar spectrum...and additional gains could be had by using networks of tubes. The down side, is you still need a lithographically defined set of metal gates on a wafer for your source and drain, so it's not quite at the point of being a totally bottom-up self assembly.