In 2015, Ali javey, a professor at UC Berkeley's school of electrical engineering and computer science, published a paper in the journal science revealing the possibility of using mono layer semiconductor to make ultra-thin LEDs. But the technology at that time, if the size of the single-layer semiconductor increases, its thickness will also increase at the same time, the real application is limited.
Recently, its team said it had succeeded in making LEDs that could expand both length and width without affecting thickness and were only three atoms thick. The new findings are published in the journal nature communication s.
Leds
When a voltage is applied to the LEDs, the electrons reach an excited state and then decay back to the ground state when they meet the hole at the point of contact, releasing energy in the form of light. This is how LEDs work. Therefore, the most difficult problem in improving the luminous efficiency of LEDs is how to make free electrons more efficiently contact the holes. Especially when the size of the semiconductor is only a single layer thick, there are not many materials available therein, making it more difficult.
Single layer semiconductor
However, the researchers use transition - metal disulfide ( TMD cs ) as a single-layer semiconductor, which has similar semiconductor properties to graphene and is considered to be an important optoelectronic material for the next generation. Then gate and source are placed on top and bottom of the semiconductor to form LEDs. when AC is indirectly connected between the gate and source, free electrons and holes appear in the middle of the single-layer semiconductor at the same time, which releases energy to light.
The configuration of this LEDs.
Future development
At present, the LEDs still need continuous improvement in many areas, especially its energy efficiency is currently only 1 %, far less than the commercial 25 ~ 30 %. But as der - sheen lien, a postdoctoral researcher on his team, said: " this material is fairly thin and elastic, so it can be made transparent and applied to curved surfaces.". At present, transparent displays have become a new target in the scientific and technological community, and the research results will have a considerable impact.
In addition, high quality TMD cs has been fabricated by chemical vapor deposition ( CVD ), so it is expected to solve the physical limit problems of integrated circuits by its characteristics.