PHOTOVOLTAICS


have stacked trays of tested cells, so there are no operators doing anything.


Ambient’s partnership with Google will utilise bifacial solar cell technology, meaning that both sides of the cell collect light. Can you explain how this capability works? The DSC itself is intrinsically bifacial, but what makes our implementation special is the way that it’s instantiated in the device. We had to get really smart about not only the solar technology, but everything else that would get it to market. We got really good at designing printed circuit boards and putting together energy-harvesting chips and building energy-harvesting subsystems to go alongside our photovoltaic cell. If you Google ‘solar powered keyboards’ or remotes, you will see pictures of old-school devices with this huge solar cell stuck on top. It’s always been our vision that we’re not trying to create a solar powered version of each of


these devices, we’re trying to be the mainstream way that these things are powered. If that’s your ambition, it’s not just the electronic integration, but also the mechanical integration and the industrial design – that’s what really makes the bifacial design work at scale.


What applications could these bifacial cells be used in? In 2021, Samsung announced that they were replacing the batteries in their TV remotes with a solar cell and a capacitor. The solar cell had to be on the back because they were using the old tech so it’s a huge solar cell. But, of course, if the remote is facing upwards – the way you normally put it on your coffee table – it doesn’t get any light. This is a perfect opportunity


for a bifacial cell. We have a TV remote that has an aperture on the back and the front, so it’s exposed to light on both sides. Another great example is electronic shelf labels in grocery stores. A store could have 50,000 tags, whose batteries


FEATURE


A double-sided solar cell


have to be changed but the problem with the solar-powered shelf labels is that the solar cell takes up valuable space on the front of the device. We’ve been able to mount the bifacial solar cell on the back, and even though it’s behind the display, it’s still getting light.


What can we expect from Ambient in the future? We’ve just opened our factory, so that’s very exciting. Showing that we could manufacture our product here in the US and still deliver the target economics at a great price point is something


A single-sided solar cell


that’s really important to us. The specifics of the Google collaboration will be announced in the coming months, but it’s a device that uses our cell. We have been focused on computer mice, remote controls, electronic shelf labels and IT sensors. And we will be ramping up these initial applications to volume this year and you’ll be seeing the first products in the market later this year. EO


Making photovoltaics microscale with 3D architecture


Making solar cells much smaller could generate electricity more efficiently, but it won’t be without challenges, the University of Ottawa’s Mathieu de Lafontaine tells Katharine Skipper


www.electrooptics.com H


ow small can you make a solar cell? Microscale photovoltaics could


offer superior efficiency, but the electrical contacts on the front of a standard solar cell can’t be easily scaled down, which means that more and more of the device is covered up as it gets smaller.


But in a paper published in


Cell Reports Physical Science, a team from Canada and France reports it has built a solar cell the width of a few human hairs with a 3D architecture that moves the electrical contacts to the back, meaning they don’t shade the face of the cell. They achieve this in III-V


semiconductor material, which can harvest a wide spectrum of light, but is less established than silicon technology. Researchers report that, compared with the standard 2D architecture, their device reduced shadowing by the electrodes by 95%. The work was a collaboration


between the University of Ottawa, the Université de Sherbrooke in Quebec and the Laboratoire des Technologies de la Microélectronique in Grenoble, France. We spoke to Mathieu de Lafontaine, a postdoctoral researcher and part-time physics professor at the University of Ottawa, who was the lead researcher


Mathieu de Lafontaine


on the paper. We asked him about the biggest challenges of the ambitious project, the applications they foresee for this technology, and their plans


May 2024 Electro Optics 23


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Ambient Photonics


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