Quantum Leap in Nanocrystal Research Opens Doors to New Materials

Researchers from a cross-institutional team have unveiled a groundbreaking approach to creating quantum dots – Molten Salt Quantum Dot Synthesis forms its basis. This effort was led by the University of Chicago. Moreover, these tiny semiconductive nanocrystals power lasers, QLED displays, solar cells, and more. In addition, their new method was recently published in Science. Specifically, the process involves superheating table salt until it becomes molten. Consequently, researchers can now synthesize materials once out of reach using traditional solvents.

Traditional quantum dot growth typically employs organic solvents that cannot withstand the extreme temperatures required to form specific nanocrystals. By contrast, molten salt remains stable and liquid at much higher temperatures. According to Prof. Dmitri Talapin from the University of Chicago’s Pritzker School of Molecular Engineering, heating salt to an extreme temperature transforms it into a colorless liquid with a viscosity resembling water.

This innovation lets scientists create nanocrystals from “III-V” elements—found in the third and fifth groups of the periodic table—long prized for their role in the fastest electronics, most powerful semiconductor lasers, brightest LEDs, and most efficient solar cells. Harnessing molten salt overcomes temperature barriers, revealing new possibilities for high-performance devices.

Quantum dots made from “II-VI” materials have long dominated research and development. These materials are composed of elements from the second and sixth groups of the periodic table. Consequently, these nanocrystals power commercial applications like QLED televisions. In addition, they have been recognized by the 2023 Nobel Prize in Chemistry. Yet, many researchers, including UC Berkeley Professor Eran Rabani, remain unconvinced. They argue that scientists must look beyond II-VI compositions. This expansion, they believe, is crucial to truly unlock the potential of quantum dots.

Now, an interdisciplinary team offers a breakthrough. They can grow nanocrystals from gallium arsenide, indium phosphide, and other III-V combinations. Notably, these elements already outperform older materials in large-scale electronic components. Furthermore, their quantum dot versions could usher in the next wave of innovation.

One major reason molten salt has been overlooked is its strong polarity. The positively and negatively charged ions in salt exert a powerful pull on any particles in the liquid. Early theories suggested that nanocrystals with relatively small surface charges would be overwhelmed and crushed. Surprisingly, experiments showed these growing crystals can indeed hold their shape and stabilize, indicating the pull of the ions is not insurmountable.

“This is very contradictory to what scientists traditionally think about these systems,” remarked UChicago graduate student and paper co-author Zirui Zhou. “Yet, our results show that we can form stable materials even under these conditions.”

Beyond immediate commercial uses, these nanocrystals could transform medical imaging devices and solar panels. In fact, their real significance lies in the sheer variety of new compositions now accessible. “We have unlocked a dozen new nanocrystal compositions,” said Dr. Justin Ondry. He is the lead author and was formerly in the Talapin Lab.

Such expansions in available materials could catalyze advances in classical and quantum computing. Furthermore, faster and more energy-efficient processors may emerge from this groundbreaking approach. Additionally, improved display technologies and superior energy-harvesting solutions could also benefit.

By reimagining salt as a high-temperature solvent, scientists have opened an exciting new frontier. This advance could reshape the future of electronics and photonics. As this technique spreads, it promises to drive a new era of discovery. Indeed, these materials can now be grown, studied, and deployed in modern devices.

1. Ondry, J. C., Zhou, Z., Lin, K., Gupta, A., Chang, J. H., Wu, H., Jeong, A., Hammel, B. F., Wang, D., Fry, H. C., Yazdi, S., Dukovic, G., Schaller, R. D., Rabani, E., & Talapin, D. V. (2024).
   Reductive pathways in molten inorganic salts enable colloidal synthesis of III-V semiconductor nanocrystals.
   Science. doi:10.1126/science.ado7088

2. University of Chicago. (2024, November 27).
   Quantum Breakthrough Allows Researchers To Create “Previously Unimaginable Nanocrystals”.