In 2015, Professor Ali Javey of the School of Electrical Engineering and Computer Science at the University of California, Berkeley (UC Berkeley), published a paper in Science, revealing the use of monolayer semiconductors to make ultra-thin Possibility of LEDs. However, the technology at that time, if the size of a single-layer semiconductor is enlarged, its thickness will also increase at the same time, and its real application is limited.
A few days ago, its team said that it has successfully made LEDs that can expand the length and width without affecting the thickness, and are only three atoms thick. The new research results have been published in the journal Nature Communications.
LEDs
When a voltage is applied to LEDs, the electrons reach an excited state, then when they meet the hole at the contact point, they decay back to the ground state, releasing their 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 and holes more efficiently contact. Especially when the size of the semiconductor is only a single layer thick, there are not many materials that can be used, which makes the difficulty even more difficult.
single layer semiconductor
The researchers used transition metal dichalcogenides (TMDCs) to make single-layer semiconductors. This material has semiconductor properties similar to graphene and is considered to be an important next-generation optoelectronic material. Then place the gate (Gate) and the source (Source) on the top and bottom of the semiconductor to make LEDs. When the alternating current is connected between the gate and the source, free electrons and holes will appear in the middle single-layer semiconductor at the same time, and then Let it release energy as light.
The configuration of the LEDs.
future development
At present, there are still many places to be continuously improved in this LEDs, especially its energy efficiency is only 1% at present, which is far lower than the 25-30% of commercially available LEDs. But as Der-Hsien Lien, a postdoctoral researcher in his research team, said: “The material is quite thin and elastic, so it can be made transparent and applied to curved surfaces.” Transparent displays have become a new goal in the scientific and technological community, and the results of this study will have considerable impact.
In addition, there have been researches to produce a large number of high-quality TMDCs through chemical vapor led display design deposition, so it is expected to use their characteristics to solve the physical limit problem faced by current integrated circuits.