News and Press Releases
11 April 2018
Green Science Alliance Co., Ltd. can Manufacture a Quantum Dot-Polyethylene Composite

Quantum dots are extremely small fluorescent nanoparticles (nano-sized crystals) typically between 10 to 10000 atoms (2 to 9 nanometers) in diameter. They are so small that one cannot see them with a typical microscope. As such, we cannot ignore the effects resulting from the extremely small size of these nanoparticles. The electronic characteristics of quantum dots are determined by their chemical composition, size, and shape. This means that we can control the color of light given off by a quantum dot solely by changing its size. Bigger dots emit longer wavelength colors, such as red, while smaller dots emit shorter wavelengths, resulting in the expression of such colors as green or blue. This means that light may be converted into nearly any color in the spectrum ranging from the UV to the IR region. Quantum dots also possess a very narrow half width and high quantum efficiency compared to ordinary solid fluorescent pigments, such that their applications could include solar cells, medical devices, bioimaging (including the imaging of cancer cells, protein analysis, cell tracking, etc.), quantum computers, security inks, quantum dot lasers, photonic crystals, LEDs, thermoelectric materials, and artificial photosynthesis, among others.

At present, few commercialized companies that synthesize quantum dots exist. Quantum dots generally exist as dispersed nanoparticles in water or any other kind of organic solvent, and therefore they can be applied towards printing or coating procedures. However, quantum dots possess poor lightfastness, as well as poor water and heat resistance, especially when printed or coated onto a substrate. 

Recently, Dr. Ryohei Mori at Green Science Alliance Co., Ltd. has established the industrial procedure to manufacture a quantum dots-resin composite (masterbatch) for the first time ever. As the quantum dots have been solidified in this product, their aforementioned weaknesses points are expected to have been improved upon. This material can also now be made into sheets or molded into shapes with greater ease. For example, quantum dot sheets for use as displays are made by a complicated process involving quantum dot ink preparation, a UV curing process, and a barrier film coating process. Now, however, a quantum dot sheet can be prepared via a simple molding process, and the quantum dots is protected by the resin around. To put it simply, quantum dot-resin composites can accelerate our ability to apply quantum dots in the real world. Green Science Alliance Co., Ltd. has made composites composed of perovskite quantum dots and polyethylene. The concentration of perovskite quantum dots is less than 0.5%. This material exhibits a high quantum efficiency with a narrow half width (19-23 nm), similar to that of quantum dots dispersed in a liquid. 

Green Science Alliance Co., Ltd. Has also synthesized semiconductor type quantum dots such as ZnS, InP/ZnS, CdS, CdSe, CuInS2(CIS), CuInSe2, CuInS2/ZnS, PbS, and AgInS2, among others. This company has also synthesized silicon quantum dots, as well as carbon-based quantum dots including graphene quantum dots. They will next attempt to create quantum dot-resin composites (masterbatch) using different kinds of quantum dots and resins.

Source: Green Science Alliance Co., Ltd