Joint development agreement for research into quantum dots for solar modules.

Looking to evolve its already impressive proprietary cadmium-telluride thin-film solar technology, First Solar Inc. has partnered with UbiQD Inc., a New Mexico-based nanotechnology company, to explore the possibilities of incorporating quantum dot technology into a next-gen solar system.

In its simplest form, a quantum dot is a man-made nanoscale crystal that can conduct electricity, consisting of a semiconductor core covered with organic molecules. For perspective, quantum dots are so small that it would take 100,000 of them to span one fingernail.

As one of the central topics in nanotechnology, it was found that when quantum dots are illuminated by ultraviolet light, the electron within becomes excited to a state of higher energy resulting in a resonance that causes the dot to emit color – the difference in the frequency of light, the difference in output color.

This technology has already been implemented in some consumer products, such as QLED TVs.

First Solar is interested in attempting to incorporate the abilities of this light-sensitive crystal into a technology that would undoubtedly benefit from absorbing more light.

"As we work towards developing the next generation of photovoltaics, we are exploring a range of enhancements that could allow us to convert more sunlight into energy," said First Solar Chief Technology Officer Markus Gloeckler. "We are interested in the potential use of quantum dots in optimizing the absorption of light and look forward to continuing our work with UbiQD on exploring this possibility."

So how could an incalculable volume of quantum dots benefit solar panels?

Physics limitation

First, it is important to note that the efficiency of a solar panel is a matter of area and not power-meaning a 10% efficient 100-watt panel and a 20% efficient 100 W panel will both produce exactly the same amount of power. However, the 20% efficient solar panel will theoretically be half the size of the 10% efficient panel.

To determine the efficiency of the panel, it is as simple as comparing the energy the sun provides to the panel to the electricity that is produced.

Therefore, if a panel was able to convert all light that shines on it into electricity, then that panel would be 100% efficient. Unfortunately, this level of efficiency has been determined to be impossible.

The theoretical maximum efficiency of a solar cell made of an ideal material is 33.7% - known as the Shockley-Quiesser limit; this is a consequence of the laws of physics and how solar cells absorb power.

Despite this theory, multi-layered solar cells can exceed this limit in lab conditions but are significantly harder to manufacture and much more expensive, so they are typically only used for satellites and other high-tech systems where space is extremely limited.

But what if there was a technology that could catch the waste light that is not absorbed by the primary solar cells?

That's exactly what First Solar is going to find out.

Quantum solar panels

While silicon-based solar panels have reached an upper limit of about 32% efficiency, just shy of the maximum theoretical limit, cadmium-telluride cells are approaching 20%, with First Solar forecasting its modules to reach 25% by 2025 with the potential for 28% by 2030.

But with the help of quantum dots, while efficiency may not improve, its output may be able to increase. And given the relative inexpensiveness of these solar cells, if quantum dots can be produced similarly cheaply, the output energy could possibly offset this new manufacturing cost.

This may be the case as typical quantum dots are made of binary components such as lead sulfide (lead and sulfur), lead selenide (lead and selenium), indium arsenide (indium and arsenic), indium phosphide (indium and phosphorous), cadmium selenide (cadmium and selenium), cadmium sulfide (cadmium and sulfur) and finally cadmium telluride (cadmium and tellurium), the very same material that has made First Solar's technology so competitive.

To add to the potential, research has already shown that quantum dots can be used in light fusion (or photochemical upconversion), where "wasted" light is upconverted into power for a solar cell.

This light fusion process uses a light "sensitizer" and light "emitter" to convert photons lower than a solar cell's bandgap or its light-absorbing sweet spot, which would otherwise not be converted into current, into the ideal-ranged photons. This would then increase the possible amount of light that a cell can use productively, hence its efficiency.

With First Solar's CdTe cells, its bandgap is closest to the optimal wavelength for converting sunlight to electricity – and with the possibility of quantum dots light fusion, anything not within this wavelength could be recaptured, increasing its output energy.

Ubiquitous Quantum Dots

Founded in 2014, UbiQD (short for Ubiquitous Quantum Dots) is a startup spun out from technology it licensed that was developed at Los Alamos National Laboratory and Massachusetts Institute of Technology.

Located in Los Alamos, New Mexico, UbiQD has already had success in nanoscale energy, installing energy-producing windows in 2021 at three commercial sites – something they call WENDOWs.

Collaborating with the United States Air Force, the company's technology was also used in a Small Business Innovation Research project in 2022, which provided funding for the installation of over 20 WENDOWs and additional scale-up and development funding for the product.

That same year, UbiQD also announced it was developing a solution for controlled-environment agriculture in partnership with Heliene, another U.S.-based solar module manufacturer.

Now, partnering with First Solar, its portfolio continues to grow, and with the possibility to improve the already impressive and quickly growing CdTe thin-film solar panels produced by America's solar company, which recently announced a $1.1 billion solar plant to be built in Louisiana, this is a significant opportunity for the quantum company.

"If successful, this application in solar modules could be a perfect example of the broad applicability of our core technology," said UbiQD CEO Hunter McDaniel. "With emerging applications in food and energy, these novel nanomaterials are proving to be a key tool in humanity's urgent response to climate change and further sustainable economic development."