Transcript
Even as the 2014 Nobel Prize in Physics was enshrining light emitting diodes (LEDs) as the single most significant and disruptive energy-efficient lighting solution of the past 100 years, scientists around the world continue to search for the even better bulbs of tomorrow.
Electronics based on carbon, especially carbon nanotubes, are emerging as successors to silicon for making semiconductor materials. And they may soon enable a new generation of brighter, low-power, low-cost lighting devices that could challenge the dominance of LEDs in the future and help meet society's ever-escalating demand for greener bulbs.
In a recent edition of the journal Review of Scientific Instruments, scientists from Tohoku University in Japan detailed the fabrication and optimization of the device, which is based on a phosphor screen and single-walled carbon nanotubes as electrodes in a diode structure.
It is essentially a field of tungsten filaments shrunk to microscopic proportions. This new type of energy-efficient flat light source has a power consumption about 100 times lower than that of an LED.
The researchers assembled the device from highly crystalline single-walled carbon nanotubes, dispersed in an organic solvent, mixed with a soap-like chemical known as a surfactant.
Then, they "painted" the mixture onto the positive electrode or cathode, and scratched the surface with sandpaper to form a light panel capable of producing a large, stable, and homogenous emission current with low energy consumption.
The new devices have luminescence systems that function like the cathode ray tubes (CRTs) used in computer monitors and TVs until a decade ago. The carbon nanotubes act like the cathodes of CRTs, and a phosphor screen in a vacuum cavity acts like the anode.
Under a strong electric field, the carbon nanotubes emit tight, high-speed beams of electrons through their sharp nanotube tips - a phenomenon called "field emission." The electrons then fly through the vacuum in the cavity, and hit the phosphor screen, making it glow.
Many researchers have attempted to construct light sources with carbon nanotubes as field emitters. But nobody has developed an equivalent and simpler lighting device.
This could well prove to be a major game-changer for the lighting industry.
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