A more environmentally sustainable technique to tune the optical properties of quantum dots via light recently developed by North Carolina State University researchers also speeds the process and improves their energy efficiency.
Quantum dots are among the most impressive breakthroughs in modern materials science, thanks to their extraordinary versatility for optoelectronics applications—from advanced displays and lighting to quantum technologies and renewable energy.
“Our inspiration for our work came from the desire to tackle key challenges around sustainable manufacturing and precision tuning of these materials to unlock their full potential,” says Milad Abolhasani, a professor of chemical and biomolecular engineering.
His group’s work focuses on metal halide perovskite quantum dots—ionic nanomaterials with exceptional optical and electronic properties highly attractive for next-gen devices.
Tune the bandgap
Quantum dots are nanoscale crystals with optical properties governed by their size and chemical composition. “The core concept behind our work is that by tuning the bandgap—the energy difference between a bound electron and a free electron state—we can control the specific color of light quantum dots can emit or absorb,” explains Abolhasani.
How does the group’s tuning method work? It relies on a photo-induced anion exchange reaction (PIAER) method to leverage light to trigger reactions within quantum dot solutions within the presence of specific halogen-containing solvents. Using light to drive the reaction requires less energy than other alternatives and allows the researchers to be extremely precise.
To do this, the researchers first place green-emitting perovskite quantum dots into a solution of chlorine or iodine and then run it through a microfluidic system that uses a light source to ensure uniform light exposure across small solution volumes (~10 microliters per reaction droplet). Small volume is the key to ensure light penetrates the entire sample and photochemical reactions will occur rapidly for the entire sample.
Light then triggers reactions that move green-emitting perovskite quantum dots closer to the blue end of the spectrum if the solvent contains chlorine, and closer to the red end of the spectrum if it contains iodine.
“By controlling the wavelength and intensity of light, we precisely alter the quantum dots’ chemical environment and shift their emitted color toward the blue or red end of the spectrum,” Abolhasani says. “Our microfluidic-based approach ensures uniform exposure to the activating light and results in consistent and high-quality materials.”
One significant challenge for the team was to ensure uniformity and precision for bandgap tuning across different batches of quantum dots. Integrating photochemistry with microfluidics required meticulous optimizations of reactor design, flow conditions, and reaction kinetics to achieve consistent, scalable results. Overcoming these hurdles required a highly interdisciplinary approach that combines chemistry, materials science, and engineering.
Photocatalysts
The coolest aspect of the group’s quantum dot bandgap tuning work? “Discovering that the quantum dots themselves can act as photocatalysts—and directly participate in reactions to modify their own properties,” says Abolhasani. “This realization was a significant ‘a-ha’ moment, which gave us an exciting glimpse into new self-driven chemical processes. The feeling was truly exhilarating, knowing we were not only observing quantum dots but actively guiding their transformations at a fundamental level.”
This short video shows the photocatalysis process. (Credit: Milad Abolhasani)
Applications for the group’s work are broad and span next-generation light-emitting diodes (LEDs), energy-efficient displays, solar cells, and emerging quantum technologies. “Given our method’s scalability and sustainability, we anticipate practical applications could emerge within the next three to five years as we move toward commercialization and integration into optoelectronic devices,” says Abolhasani.
What’s next? “Scaling the technology to industrially relevant levels and further expanding the versatility of our approach,” Abolhasani says. “We’re actively exploring new chemical pathways and materials to expand the applicability of photo-driven quantum dot tuning—ultimately aiming to drive forward sustainable innovation in optoelectronics and beyond.”
FURTHER READING
P. Jha et al., Adv. Mater. (2025); https://doi.org/10.1002/adma.202419668.
Sally Cole Johnson | Editor in Chief
Sally Cole Johnson, Laser Focus World’s editor in chief, is a science and technology journalist who specializes in physics and semiconductors. She wrote for the American Institute of Physics for more than 15 years, complexity for the Santa Fe Institute, and theoretical physics and neuroscience for the Kavli Foundation.