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Department of Energy Early Career Award Recipient to Study Custom Composite Nanocrystals

August 15, 2023

Department of Energy Early Career Award Recipient to Study Custom Composite Nanocrystals

University of Oklahoma professor develops chocolate chip cookie-like nanocrystal structure to improve photonic power for quantum communications.

Yitong Dong, Ph.D.
OU professor Yitong Dong demonstrating nanocrystal spectroscopy in his lab. Credit: Josh DeLozier

Yitong Dong, Ph.D., assistant professor in the Department of Chemistry and Biochemistry, Dodge Family College of Arts and Sciences at the University of Oklahoma, is the only recipient in the state of Oklahoma to have been selected for funding through the 2023 Department of Energy’s Early Career Research Program.

Nanocrystals are a type of building block of nanotechnology that can be used to improve secure communications. Dong’s research group has developed a unique capability to produce extremely small nanocrystals that could enhance the purity of single photon emissions and advance capabilities toward scalable, room-temperature quantum communications.

“The future of quantum information science will enable us to encrypt our information communication in a nearly perfect way that it can never be hacked or eavesdropped,” Dong said. “This relies on quantum light sources, but current quantum light sources have to work at very low temperatures that usually require liquid helium and an ultra-high vacuum to have sufficient emission efficiencies, so that's going to be very expensive if we're looking at scalable quantum communication devices. Our nanocrystals, on the other hand, can emit light at room temperature with really high efficiencies.” 

By adjusting the size of these nanocrystals, some as small as several billionths of a meter, Dong’s research group is studying how the nanocrystals' surface influences how they emit light.

“For this project, we synthesized a very special nanocrystal called perovskite nanocrystal,” Dong said. “They are very, very bright. How they emit light and the color of the light emitted will change as a function of their sizes. As a nanocrystal materials research group, we can make billions or trillions of them with almost identical size, and then we can control their surface.”

Left: Nanocrystal luminescing in solution. Right: Nanocrystal luminescing in solution following synthesis.
Left: Nanocrystal luminescing in solution. Right: Nanocrystal luminescing in solution following synthesis.
Close-up “chocolate chip cookie” structure of composite nanocrystals.
Close-up “chocolate chip cookie” structure of composite nanocrystals.

Perovskite nanocrystals are easy to make and easily malleable. However, the surface lattices – the crystal units along the surface area of each nanocrystal – vary in their flexibility, which affects their single photon emission performance. The ability to customize the light emitted from these nanocrystals is an important requirement for quantum information network construction and a current gap in the field.

“Our research is targeting the development of single photon emitters using our nanocrystals, which are cheap and work at room temperatures, to enable the future construction of scalable quantum information networks,” Dong said. “What we propose to do in this project is to use a supramolecular matrix where we can embed our tiny nanocrystals into this matrix, and the matrix can rigidify the surface lattice of the nanocrystals.”

This composite material, Dong says, resembles a chocolate chip cookie. “By tuning the rigidity of the supramolecular matrix (the cookie bread), it will anchor the surface of the nanocrystals (chocolate chips) embedded inside of it and thereby rigidify the surface.”

Then, in addition to measuring the stability of this composite material, they will study how the changes in surface rigidity change the single photon emission properties, such as brightness and purity.

“In the end, we're targeting photo coherence,” he said. “Are the photons emitted from the same nanocrystal all the same in terms of their phase and wavelength? If they’re all the same, they’re going to be very useful for the future of quantum computing and quantum communications.”

Yitong Dong is the principal investigator of the project, “Understanding the relationship between surface lattice rigidity and single photon emission dynamics in strongly confined cesium lead bromide perovskite quantum dots.” The five-year project is expected to receive approximately $875,000 from the Office of Basic Energy Sciences through the Department of Energy’s Early Career Research Program, beginning July 1, 2023, through June 30, 2028. Dong is one of 93 early career scientists selected to receive a combined $135 million in funding from the 2023 DOE Early Career Research Program designed to develop the next generation of STEM leaders to solidify America’s role as the driver of science and innovation around the world.