A team led by Professor Milad Abolhasani at North Carolina State University has demonstrated a new approach that uses light to adjust the optical properties of perovskite quantum dots. Their method operates via a microfluidic, light-activated process, offering a faster, lower-energy pathway to tune bandgaps compared to conventional chemical or thermal methods.
Jha, P., Mukhin, N., Ghorai, A., Morshedian, H., Canty, R. B., Delgado‐Licona, F., Brown, E. E., Pyrch, A. J., Castellano, F. N., & Abolhasani, M. (2025). Photo‐Induced Bandgap Engineering of Metal Halide Perovskite Quantum Dots In Flow. Advanced Materials, 37(16). https://doi.org/10.1002/adma.202419668
Traditionally, tuning the emission wavelength (i.e. bandgap) of quantum dots has relied on chemical doping, high-temperature annealing, or ion exchange under controlled but energy-intensive conditions. In their recent work, Abolhasani’s group engineered a system where quantum dots immersed in a solvent with halide species (chlorine, iodine) are passed through a microfluidic channel illuminated by light. This induces anion exchange—chloride or iodide ions replace existing halides in the dot lattice; shifting the bandgap toward blue or red, respectively.
Milad Abolhasani ALCOA Professor of Chemical and Biomolecular Engineering at NC State stated,
“The discovery of quantum dots earned the Nobel Prize in chemistry in 2023 because they are used in so many applications. Existing methods for bandgap tuning of perovskite quantum dots rely on chemical modifications or high-temperature reactions, both of which are energy-intensive and can introduce inconsistencies in the final material properties.”
The microfluidic environment is key. The small reaction volumes (on the order of 10 µL per droplet) enable uniform light penetration and rapid photochemical conversion. Because the reaction is driven by light (rather than heat or strong reagents), the process can be more controlled, efficient, and less disruptive to the quantum dot structure.
In experiments, the researchers showed that this photo-induced bandgap engineering (PIAER) approach can adjust quantum dot emission across the visible spectrum with good precision, while preserving photoluminescence quality. They also report that reaction rates in the flow system exceed those of conventional batch setups by several fold.
Detailed characterization (in situ and ex situ) allowed the team to probe how photon flux, halide concentration, and solvent environment affect kinetics and final optical properties. They observed that higher photon flux speeds up anion exchange, but also must be balanced to avoid side reactions. The choice of haloalkane, additive ligands, and the solvent matrix also influence the ion exchange pathways and defect formation.
Further mechanistic studies, including recent investigations into solvent-mediated exchange dynamics, help clarify how light triggers bond cleavage and ion migration in the perovskite lattice. These insights are important because they guide how to optimize conditions without degrading dot quality or causing unintended phases.
In one promising extension, the team demonstrated the exchange of bromide to iodide in lead halide perovskite dots in a light-driven process, aided by a thiol additive that helps stabilize the surface and facilitate ion exchange. They also used intensified flow reactors to reduce precursor usage by orders of magnitude, pointing toward scalable manufacturing routes.
Quantum dots are central to many optoelectronic technologies; LEDs, displays, solar cells, quantum emitters, sensors; where precise control over emission wavelength is critical. A method that can reliably and gently tune quantum dots post-synthesis offers flexibility: manufacturers could produce a base batch of dots and later tailor them for specific applications via light-based adjustment.
Because the new approach demands less energy and has lower chemical overhead, it also aligns with sustainability goals. It could shorten processing steps, reduce waste, and improve yield in industrial settings. For labs working on quantum devices, the ability to fine-tune dot spectra without damaging the material is particularly valuable.
Scaling remains a central challenge. While microfluidic flow enables precise control at small scale, transferring that into high-throughput production will require robust reactor design, parallelization, and stable light delivery systems. Ensuring uniform exposure and minimizing deviations across channels will be critical.
Another concern is long-term stability. Ion exchange under illumination can introduce defects, lattice strain, or diffusion of unwanted species. The team must show that tuned quantum dots retain their optical performance over long periods and under operational stresses.
There is also room to explore other compositions, including lead-free perovskites or different halide systems, to extend the method’s generality. The mechanism of light-triggered exchange under various chemistries is still being unraveled, and controlling side reactions will demand further study.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
