Researchers from MIPT and the RAS Institute of Problems of Chemical Physics have come up with a simple and convenient way to get the arbitrary quantum points needed for physical experiments over chemical aging. The study was published in Chemicals Now,
Colloidal quantum dots are nanosized crystals that are the right size at the frequency they emit and absorb electromagnetic radiation. It is used in solar cells, TV sets, fire alarm systems, and much more.
MIPT Laboratory for Photonics of Quantum Nanostructures conducted research using lead quantum sulfide dots. The conventional approach to synthesis, known as heat injection, involves a mixture of two so-called precursors – compounds containing lead and sulfur – under special conditions. This process is controlled using special reagents and tools to create the desired quantum dots. However, the synthesis is complex, expensive, and does not produce the point of all the measurements required.
“If a physicist needs some quantum dots but does not have the tools to do so, it usually costs a lot of money to synthesize commissions or order products from abroad through catalogs. And you can not buy dots of arbitrary size,” said Ivan Shuklov, deputy head of the MIPT Laboratory for Photonics of Quantum Nanostrukturures. “So we are looking for a simple and affordable way to get lead quantum sulfide points that do not require special equipment or care and will produce points of the size and exact properties needed.”
Experimenting with various compounds, the researchers found that the quantum point spectrum may change the presence of oleic mixtures. sour and oleylamine. The electron microscope has a closer look at what is happening, indicating that the mixture of the two chemicals to completely reverse the standard synthesis, causes the sulfur and lead atoms to recede into the solution, gradually reducing the point size. More importantly, the point size distribution remains the same. In other words, you got basically the same points that you had before introducing the mix, only that they were smaller and thus changed them.
The standard approach to synthesis of quantum dots also works with oleic acid and oleylamine, but its chemicals work at different stages. It is a simultaneous application and interaction of each other that apparently activates controlled crystal aging. That is, predictable long-term changes in crystal properties over time.
“We have proposed a solution that allows experiments with 10-nanometer quantum dots to be reduced to 8 nanometers in the morning, to 6 nanometers the day after, and so on. Accordingly, the absorption frequency will change from 2 micrometers to the first 1.8 micrometers. to be 1.5 micrometers, “explained Vladimir Razumov, head of the Photonics Laboratory of Quantum Nanostructures at MIPT. “Basically, from a set of common colloidal quantum points, you can produce exactly the right size and properties for your needs. With our technique, a physicist who does not have special equipment other than a few test tubes can convert an example of quantum points to size What is needed is to wait for the ‘age’ points of the right size. “
References: “Aging controlled by PbS colloidal quantum dots under mild conditions” by IA Shuklov, VF Toknova, AA Lizunova and VF Razumov, 5 October 2020, Chemicals Now,
DOI: 10.1016 / j.mtchem.2020.100357