Getting old quantum dots. Photograph credit score: Daria Sokol / MIPT Press Workplace
Researchers from the MIPT and the RAS Institute for Issues in Chemical Physics have proposed a easy and handy solution to get hold of quantum dots of any measurement required for bodily experiments by means of chemical growing older. The research was revealed in Supplies immediately chemistry.
Colloidal quantum dots are nano-sized crystals, the scale of which determines the frequency with which they emit and soak up electromagnetic radiation. They’re used in photo voltaic cells, televisions, fireplace alarm methods, and extra.
The MIPT Laboratory for Photonics of Quantum Nanostructures conducts analysis utilizing lead sulfide quantum dots. The normal strategy to their synthesis, generally known as sizzling injection, includes mixing two so-called precursors – compounds containing lead and sulfur – below sure situations. This course of is managed utilizing particular reagents and gear to create quantum dots of the specified measurement. Nonetheless, the synthesis is advanced, costly, and doesn’t present factors of all required sizes.
“When a physicist wanted some quantum dots however did not have the gear to make them, he used to spend a lot of cash to fee the synthesis or to order the merchandise from overseas by way of a catalog. And also you could not purchase dots of any measurement, ”stated Ivan Shuklov, deputy director of the MIPT laboratory for photonics of quantum nanostructures. “That’s the reason we have been on the lookout for a easy and cheap solution to get hold of lead sulfide quantum dots that did not require any particular gear or expertise and that may create dots of any measurement and subsequently exactly the required properties.”
When experimenting with completely different compounds, the researchers discovered that the quantum dot spectrum adjustments in the presence of a combination of oleic acid acid and oleylamine. Electron microscopy allowed a nearer take a look at what was taking place and confirmed that the combination of the 2 chemical compounds truly reversed the usual synthesis, inflicting sulfur and lead atoms to withdraw into the answer and step by step decreasing the spot measurement. Extra importantly, the purpose measurement distribution stayed the identical. In different phrases, you get mainly the identical factors you had earlier than you set the combination in, solely they get smaller and subsequently change their properties.
The usual strategy to quantum dots synthesis additionally makes use of oleic acid and oleylamine, however the chemical compounds are used at completely different phases. It’s their simultaneous software and mutual interplay that allows managed crystal growing older. That’s, the predictable long-term change in crystal properties over time.
“Now we have proposed a answer with which an experimenter with 10 nanometer quantum dots can predictably scale back them to eight nanometers tomorrow, to six nanometers the following day, and so forth. Accordingly, the absorption frequency adjustments the primary time from 2 micrometers to 1.8 micrometers after which to 1.5 micrometers, ”defined Vladimir Razumov, head of the laboratory for photonics of quantum nanostructures on the MIPT. “Principally, from a batch of generic colloidal quantum dots, you can also make these with precisely the appropriate measurement and properties in your wants. With our method, a physicist can convert a pattern of quantum dots into any measurement with none particular gear aside from a few test tubes. All it takes is to attend for the dots to ‘age’ to the appropriate measurement. ”
Reference: “Managed growing older of colloidal PbS quantum dots below delicate situations” by IA Shuklov, VF Toknova, AA Lizunova and VF Razumov, October 5, 2020, Supplies immediately chemistry.
DOI: 10.1016 / j.mtchem.2020.100357
