In a study published in the journal Optical Materials Express, Strathclyde researchers detail how they recycled quantum dots from spent lasers to create new ones that perform just as well as the originals.
Supraparticles suspended in water solutions under UV light. Image Credit: University of Strathclyde
Researchers have developed a means to recycle the tiny particles needed to make supraparticle lasers, which accurately regulate light on a very small scale.
The solution, financed by the Leverhulme Trust, has the potential to help manage these precious materials more sustainably.
Supraparticle lasers work by trapping light inside a tiny sphere formed of quantum dots, which are highly efficient at absorption, emission, and amplification.
They are created by combining quantum dots in a solution that allows them to cling together in tiny bubbles. However, not all attempts succeed, and even effective lasers deteriorate over time. This results in wasted materials, which can be costly.
Recycling Method
The concept of recycling these particles arose following a team discussion regarding the high cost of wasted quantum dots. Dillon Downie, a PhD student at the University of Strathclyde’s Institute of Photonics, proposed a potential solution, which was evaluated with the help of team leader Dr Nicolas Laurand. To their astonishment, they were able to recover and reuse the particles, resulting in new lasers.
Supraparticle lasers are already beginning to be used for targeted drug delivery and sensing applications, as well as for components in compact electronic systems. Nanoparticle aggregates and supraparticle lasers are expected to play an increasingly prominent role in everything from wearable medical devices to ultrabright LEDs.
Dillon Downie, PhD Student, Institute of Photonics, University of Strathclyde
He added, “Our recycling method reduces costs and environmental impact by minimizing the need for new nanoparticles and the disposal of old ones, and it should be applicable to any colloidal nanoparticle species, especially rare-earth ones.”
“We envision this method being used to extend the life cycle of supraparticles, which could be repurposed for various applications such as medical biosensors, representing a significant advance toward sustainable nanoengineering,” he further noted.
Simple Method
The recycling procedure begins by heating the spent lasers and exposing them to sound waves. The quantum dots were then separated from contaminants with a mixture of oil and water, before being filtered and coated to restore their characteristics. Finally, the researchers evaluated the recycled dots to confirm they could still emit light effectively before using them to make new lasers.
This procedure restored 85% of the original quantum dots, and they performed nearly as well as new ones. The recycled dots were then used to create lasers that performed just like the originals.
The researchers intend to investigate how recycling impacts the performance of quantum dots over time, as well as to create methods for recycling more complicated or specialized particles.
Dillon concluded, “Our simple method doesn’t need fancy equipment, so it can be used in most labs. This is a big step toward making advanced materials more sustainable.”
Journal Reference:
Downie, D. H. et. al. (2024) Recycling self-assembled colloidal quantum dot supraparticle lasers. Optical Materials Express. doi.org/10.1364/OME.537183