Ou Chen

Assistant Professor of Chemistry
Ou Chen
Assistant Professor of Chemistry
Photo: Mike Cohea/Brown University
Quantum dots — tiny light-emitting crystals — may be useful in everything from televisions to bio-imaging at the cellular level. They are among the nanoscale structures that interest Ou Chen.

Ou Chen is something of a nano-architect.

The new assistant professor of chemistry specializes in putting different types of nanoparticles together to form new structures with novel capabilities.

“I’m using nanocrystals as building blocks to make higher-order architectures, superstructures, superparticles, and superlattices,” he said. “These are new platforms where we can study nanoparticle interactions.”

Chen got started on this research path late in his graduate school career at the University of Florida. For most of his Ph.D. work, he studied the basic science behind how nanoparticles form and grow. But toward the end of his time in graduate school, his adviser gave a talk on the tiny light-emitting crystals known as quantum dots.

“He showed us these very beautiful, very colorful quantum dots,” Chen said. “Just by changing the size, he could change the color from deep blue to bright red. It was really intriguing to me.”

As a postdoctoral researcher at MIT, Chen merged his interested in nanoparticles and quantum dots — quite literally. He developed a new type of superparticle that combines a cluster of iron-oxide nanoparticles as a core with quantum dots encrusted on its outer surface. The resulting hybrid particle emits a fluorescent glow and can be manipulated using magnetic fields. It’s a potential boon for bio-imaging at the cellular level.

“You can use the magnetic field to manipulate the particles and control where they are in the cell,” Chen said. “You can use the light emission for imaging.”

At Brown, Chen plans to continue developing multifunctional particles. He remains interested in using such particles for bio-imaging and other medical applications, but he’s also interested in working on problems in energy and catalysis, where these kinds of multifunction particles have great potential.

Take for example the reaction in which water is split into constituent oxygen and hydrogen, a method of producing hydrogen fuel.

“You need one type of catalysis to do the oxidation reaction and another type of catalysis to do the hydrogen reduction reaction,” Chen said. “If you can combine the two different nanoparticles together, you could do this duel catalysis at the same time with the same catalytic system.”

That’s just the type of system Chen will look to develop at Brown.

Chen says he’s also interested in continuing research basic research on quantum dots. Quantum dot technology has come a long way in the last few years. The first quantum dot televisions have just started hitting the market.

“That’s a really good motivation for us,” he said. “That’s the first time I’ve seen a commercial product using quantum dot technology. It’s a really big move in the field.”

But there are still potential improvements to be made with quantum dots. For example, Chen is interested to see if there’s a way to make quantum dots without heavy metals.

“Heavy metals aren’t environmentally friendly materials,” he said. “Maybe we can try to develop different kinds of quantum dots without heavy metals that would be more environmentally friendly.”

Chen said he’s looking forward to working with his new colleagues at Brown on all of these challenges.