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Colloidal Quantum Dot Solar Cells Improve Energy Conversion Efficiency

Researchers claim they have developed the most efficient CQD ever

2 min read
Colloidal Quantum Dot Solar Cells Improve Energy Conversion Efficiency

Back at the end of June this year, I covered work that Edward H. Sargent and his research team at the University of Toronto conducted in making solar cells from colloidal quantum dots (CQDs) more efficient.

At that time, the solar power conversion efficiency for the device they described in their Nature Photonics article was 4.2 percent.

Now the Sargent team, along with researchers from King Abdullah University of Science & Technology (KAUST) and Pennsylvania State University (Penn State), has bumped that number up to 6 percent, creating what is claimed to be “the most efficient colloidal quantum dot (CQD) solar cell ever.”

This time, the research was published in the journal Nature Materials and showed that quantum dots could be more densely populated on a surface by using inorganic ligands in the place of organic molecules, allowing the quantum dots to be closer together.

“We wrapped a single layer of atoms around each particle. This allowed us to pack well-passivated quantum dots into a dense solid,” explained Dr. Jiang Tang, the first author of the paper, who conducted the research while a post-doctoral fellow in the Edward S. Rogers Department of Electrical and Computer Engineering at U of T.

As I mentioned in my initial piece on this line of research back in June, the Saudi Arabian government has been financing Sargent’s work in this area to the tune of US $10 million since 2008.

In this latest phase of the research, it appears KAUST was involved in the research by contributing the microscopy and visualization aspects. In addition, it seems that the licensing deal on this research is going to be shared by the University of Toronto and KAUST.

“The world—and the marketplace—need solar innovations that break the existing compromise between performance and cost. Through the partnership between U of T, MaRS Innovations, and KAUST, we are poised to translate exciting research into tangible innovations that can be commercialized,” said Sargent. 

If Sargent’s previous prediction proves correct, that these CQD materials in photovoltaics will be in building materials, mobile devices, and automobile parts in the next five years, there may some time yet before the licensing agreement will mean much. Meanwhile, inexpensive alternatives, namely dye-sensitized solar cells, are reaching 10 percent conversion efficiency now and appear poised to enter new markets. 

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Two Startups Are Bringing Fiber to the Processor

Avicena’s blue microLEDs are the dark horse in a race with Ayar Labs’ laser-based system

5 min read
Diffuse blue light shines from a patterned surface through a ring. A blue cable leads away from it.

Avicena’s microLED chiplets could one day link all the CPUs in a computer cluster together.


If a CPU in Seoul sends a byte of data to a processor in Prague, the information covers most of the distance as light, zipping along with no resistance. But put both those processors on the same motherboard, and they’ll need to communicate over energy-sapping copper, which slow the communication speeds possible within computers. Two Silicon Valley startups, Avicena and Ayar Labs, are doing something about that longstanding limit. If they succeed in their attempts to finally bring optical fiber all the way to the processor, it might not just accelerate computing—it might also remake it.

Both companies are developing fiber-connected chiplets, small chips meant to share a high-bandwidth connection with CPUs and other data-hungry silicon in a shared package. They are each ramping up production in 2023, though it may be a couple of years before we see a computer on the market with either product.

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