MIT researchers have created ultra-thin, flexible solar cells that can be printed with semiconductor inks and scalable manufacturing techniques. They are much thinner than a human hair, weigh 1% more than conventional solar panels, and generate 18 times more energy per kilogram, according to an MIT blog post.
When attached to a strong, lightweight fabric, they are easy to install on any fixed surface. They can provide power on the go as a portable power fabric or be quickly transported and deployed to remote locations for emergency assistance. Because they are so thin and light, these solar cells can be laminated to many different surfaces, from boat sails to tents and tarps deployed in disaster recovery operations. They could even be used to circumnavigate Australia. This lightweight solar technology can be easily integrated into built environments with minimal installation needs, the researchers say.
“The metrics used to evaluate a new solar cell technology are generally limited to its power conversion efficiency and its cost in dollars per watt. Just as important is integrability: the ease with which new technology can be adapted. Light solar fabrics allow integrability, giving impetus to current work. We are striving to accelerate the adoption of solar energy, given the current urgent need to deploy new carbon-free energy sources,” says Vladimir Bulović, head of emerging technology at MIT and leader of the Organic and Nanostructured Electronics Laboratory (ONE Lab). ). He is also the director of MIT.nano and lead author of a new paper describing this groundbreaking work on ultrathin solar cells.
His co-authors are Mayuran Saravanapavanantham, a graduate student in electrical engineering and computer science at MIT, and Jeremiah Mwaura, a research scientist in the MIT Electronics Research Laboratory. For readers who want to delve into the technical details of this discovery, they can find more, much more, at small methodswho published the research paper on December 9. Fortunately, the article is not behind a paywall and is accessible to anyone with an internet connection.
The path to ultra-thin solar cells
Traditional silicon solar cells are fragile, which means they have to be encased in glass and packaged in a thick aluminum frame. That makes them heavy and inflexible, which in turn limits where and how they can be implemented.
The search for printed solar cells began more than a decade ago. Six years ago, the MIT ONE Lab team produced solar cells using an emerging class of thin-film materials that were so light they could be placed on top of a soap bubble. But these ultra-thin solar cells were made using complex vacuum-based processes, which can be expensive and difficult to scale up.
To produce these new ultra-thin and flexible solar cells, nanomaterials in the form of printable electronic inks are used. Working in the MIT.nano clean room, the researchers coat the solar cell structure using a slot coater that deposits layers of electronic materials onto a prepared, releasable substrate that is only 3 microns thick. Using screen printing (a technique similar to how designs are added to screen-printed T-shirts), an electrode is deposited on the structure to complete the solar module. The researchers can then peel the printed module, which is about 15 microns thick, from the plastic substrate, forming an ultralight solar array.
Such thin, stand-alone solar modules are unwieldy and can easily tear, making deployment difficult. To solve this challenge, the MIT team searched for a high-strength, flexible, and lightweight substrate to which solar cells could be attached. They identified the fabrics as the optimal solution, as they provide mechanical resistance and flexibility with little added weight.
They found an ideal material: a composite fabric that weighs just 13 grams per square meter known commercially as Dyneema. This fabric is made of fibers that are so strong that they were used as ropes to lift the cruise ship Costa Concordia from the bottom of the Mediterranean (after her captain drove her too close to shore to greet family and friends, whereupon she collided with a rock). and sank). By adding a layer of UV-curable glue just a few microns thick, they adhere the solar modules to sheets of that fabric. This forms an ultra-light and mechanically robust solar structure.
“While it may seem simpler to print the solar cells directly onto fabric, this would limit the selection of potential fabrics or other receptive surfaces to those that are chemically and thermally compatible with all the processing steps required to fabricate the devices. Our approach decouples the manufacturing of solar cells from their final integration”, explains Saravanapavanantham.
Outshining conventional solar panels
When they tested the device, the MIT researchers found that it could generate 730 watts of power per kilogram when standing upright and around 370 watts per kilogram if deployed over heavy-duty Dyneema fabric. That’s about 18 times more than conventional solar cells in terms of power per kilogram.
“A typical rooftop solar installation in Massachusetts is about 8,000 watts. To generate the same amount of power, our fabric PV would only add about 20 kilograms (44 pounds) to the roof of a house,” explains the co-author. When tested for durability, the ultra-thin solar cells retained more than 90% of their initial power generation capabilities after being wound and unwound more than 500 times.
While MIT’s solar cells are much lighter and more flexible than traditional cells, they should be encased in another material to protect them from the environment. The carbon-based organic material used to make the cells could be modified by interacting with moisture and oxygen in the air, which could impair their performance.
“Enclosing these solar cells in heavy glass, as is standard with traditional silicon solar cells, would minimize the value of current breakthrough, so the team is developing ultra-thin packaging solutions that would only fractionally increase the weight of current ultralight devices. says Mwaura.
“We are working to remove as much of the non-solar active material as possible while still preserving the form factor and performance of these ultra-lightweight and flexible solar structures. For example, we know that the manufacturing process can be further simplified by printing the releasable substrates, equivalent to the process we use to manufacture the other layers of our device. This would speed up the translation of this technology to the market”, he adds.
We know that the “transition to market” part is often the hardest part. A review of the CleanTechnica The library reveals two stories about solar cells printed by companies that have never been heard from since: one in 2009 and one in 2016. As Tom Petty once told us, “The waiting is the hardest part.”
Do you appreciate CleanTechnica’s originality and cleantech news coverage? Consider becoming a CleanTechnica member, supporter, technician or ambassador, or a patron on Patreon.
Don’t want to miss a clean tech story? Sign up to receive daily CleanTechnica news updates by email. Or follow us on Google News!
Have a tip for CleanTechnica, want to advertise, or want to suggest a guest for our CleanTech Talk podcast? Contact us here.