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U.S. Research Team Prepared Defect-free Film of Molybdenum Disulfide

Monolithic semiconductor such as MoS2 (molybdenum disulfide) aroused the interest of many researchers, including research and development of transparent LED display, high-efficiency solar cells, photodetectors and nanotube transistors and so on. However, they suffer from defects in the semiconductor thin film, which greatly affect their performance.

Recently, the University of California at Berkeley and the Lawrence Berkeley National Laboratory engineer to lead R & D team discovered an easy way to fix defects in the thin layer of molybdenum disulfide. By immersing the material into the chemical treatment called bistriflimide (or TFSI) organic acids, which may be photoluminescence quantum yield of materials increased by 100 times.

Quantum yield is a ratio description of the input energy and the light produced by the material itself, the stronger the emitted light, the higher the quantum yield, the better the quality of the material. The quantum yield of molybdenum disulfide was strengthened by researchers, raised from less than 1% to 100%.

The results of the team in November 27^th, 2015 published in scientific issues. It opened a new chapter of molybdenum disulfide and other materials in a single layer that they can apply to high-performance transistors and optoelectronic devices.

Javi Ali is a professor at Berkeley in Electrical Engineering and Computer Science University of California, he said: "Traditionally, the thinner the material, the more sensitive to defects in the first study to demonstrate the photoelectric. Defect-free single layer of material, never heard of this before. "

It did this with an acid because by definition, an acid is usually formed when hydrogen atoms tend to some other substance "release" protons. The researchers said that this chemical reaction called protonated have to fill the missing atomic defect while removing impurities sticking to the surface effect.

The researchers claim that scientists have been engaged in a single layer of semiconductor research because they can withstand the high light transmittance and folds, bending and other limitation mechanical deformation, which makes them the device could be used in a transparent and flexible devices.

Molybdenum disulfide rely on van der Waals forces between atomic layers together, this is a powerful atomic bonds between the different layers. Another advantage of the material so thin that electrical height adjustable. For applications such as LED display, this feature allows the device to a single cell preparation can issue a wide range of light, relying solely on conventional different voltages are applied to adjust the range of the light is different.

On the other hand, LED efficiency and photoluminescence quantum yield is directly related, theoretically can use the study "defect-free" single photoelectric materials research and development of high-performance, flexible LED display, and when no power is supplied when It is transparent.

This approach also has the revolutionary potential of the transistor. As the size of computer chips in the devices become smaller and smaller, thinner, defects in the performance limitations played a greater role. Javi said: "This new development of defect-free single layer of material in addition to allowing new low-energy switch, you can also solve the defects."

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