DNA from salmon
The name organic electronics always causes confusion, with carbon-based semiconductors being confused with living things.
Maybe now the confusion has increased slightly since James Grote of the University of Dayton, USA, has used DNA to build a LED.
And the gains were not a few: the DNA has an LED light more pleasing to the human eye – is a light “warmer” – is brighter, consumes less energy and has a longer shelf life.
This is not no “LED alive”, but change is unusual: the researcher replaced the LED phosphor layer, usually made with a mixture based on epoxy, a layer of deoxyribonucleic acid (DNA), from processed eggs and salmon sperm.
This DNA is a processed product is already commercially available, manufactured in Japan from the waste of the fishing industry.
Although the production is small, more focused research, the fact of using something as a raw material that is discarded by the industry makes the material potentially very cheap.
The most surprising result of this substitution by DNA epoxy is that the epoxy layer is not just the active material emitting light.
The LED remains DNA made with the gallium nitride semiconductor, which emits blue light.
However, “a film based on the fluorescence of DNA is 100 times greater than the fluorescence of the original film,” he says.
“DNA was initially soluble only in water, so it was first precipitated with CTMA to make it insoluble in water but dissolve in organic solvents. After dissolving DNA in CTMA-butanol, we simply mix [the compound] with powder of YAG: Ce, “Grote said.
CTMA is the acronym for hexadecyltrimethylammonium chloride. And YAG: Ce refers to a compound – the yttrium-aluminum garnet doped with cerium – used to convert the light of blue LED original white light.
Conversion of the LED light
The blue light originally emitted by the gallium nitride semiconductor excites the YAG: Ce, causing a portion of blue light is converted to a light yellowish.
The yellow light stimulates the red and green receptors of the eyes, and the resulting mixture of blue and yellow gives the impression of seeing a white light. A bluish-white light, in fact, called “cold light”, which is not as pleasant to human eyes.
The new DNA-based material converts light emitted by the semiconductor light is more red, reducing or even eliminating the blue component, causing the LED emit a white light “hot”.
Furthermore, the DNA layer was more resistant to degradation than the original layer, which means that the LED will have a shelf life greater.