Scientists from Tohoku University in Japan have reported that they have developed a new type of energy-efficient flat light source based on carbon nanotubes that has about one hundredth of the power consumption of an LED.

The device is based on a phosphor screen and single-walled carbon nanotubes as electrodes in a diode structure.

A liquid containing highly crystalline single-walled carbon nanotubes is dispersed in an organic solvent mixed with a surfactant (soap-like chemical). This is “painted” onto the cathode and the surface is scratched with sandpaper to form a light panel.

This wet coating process allows fabrication of large-areas of uniformly thin films at low cost.

Under a strong electric field, the cathode emits beams of high-speed electrons through its sharp nanotube tips. The electrons then hit the phosphor screen and produce light – somewhat like a cathode ray tube on a microscopic scale and a thousand times denser.

The result is an energy-efficient flat-panel light source with very low power consumption of around 0.1 watt for every hour’s operation–about a hundred times lower than that of an LED.