Paper-thin solar cell can turn any surface into a power source – ScienceDaily

MIT engineers have developed ultralight fabric solar cells that can quickly and easily turn any surface into a power source.

These durable, flexible solar cells, which are much thinner than a human hair, can be easily mounted on a stable surface by affixing them to a strong, lightweight fabric. They can provide energy on the go as a wearable power structure, or they can be transported and quickly deployed to remote locations for assistance in emergencies. They weigh one percent of conventional solar panels, produce 18 times more power per kilogram, and are produced from semiconductor inks using printing processes that could be scaled up to large-area production in the future.

Because they are so thin and light, these solar cells can be laminated to many different surfaces. For example, they can be integrated into a boat’s sails to provide power while at sea, attached to tents and awnings used in disaster recovery operations, or applied to the wings of drones to extend their flight range. This lightweight solar technology can be easily integrated into built environments with minimal installation requirements.

“The metrics used to evaluate a new solar cell technology are typically limited to their power conversion efficiencies and costs in dollars per watt. Integration is just as important – the ease of adapting the new technology. Lightweight solar Fabrics enable integrability, accelerating existing work. New Given the current urgent need to deploy carbon-neutral energy sources, we are striving to accelerate the adoption of sunlight,” and the Laboratory of Nanostructured Electronics (ONE Lab), director of MIT.nano and senior author of a new paper describing the work.

Joining Bulović on the paper are co-lead authors Mayuran Saravanapavanantham, a graduate student in electrical engineering and computer science at MIT; and Jeremiah Mwaura, a research scientist at the MIT Electronics Research Lab. Research published today Small Methods.

weakened sun

Conventional silicon solar cells are fragile, so they must be encased in glass and packaged in a heavy, thick aluminum frame that limits where and how they can be deployed.

Six years ago, the ONE Lab team built solar cells using an emerging class of thin-film materials that were light enough to sit on top of a soap bubble. But these ultrathin solar cells were manufactured using complex, vacuum-based processes that can be expensive and difficult to scale.

In this work, they set out to develop fully printable thin-film solar cells using ink-based materials and scalable manufacturing techniques.

They use nanomaterials, in the form of printable electronic inks, to manufacture solar cells. Working in the MIT.nano clean room, they coat the solar cell structure using a slot-die coater that deposits layers of electronic materials onto a prepared, releasable substrate only 3 microns thick. Using screen printing (a technique similar to adding designs to screen printed tees), an electrode is placed on top of the structure to complete the solar module.

The researchers can then create an ultralight solar device by peeling the printed module about 15 microns thick from the plastic substrate.

However, such thin, self-contained solar modules are difficult to handle and can be easily torn, making them difficult to install. To meet this challenge, the MIT team sought a lightweight, flexible, and high-strength substrate on which to adhere solar cells. They identified fabrics as the most suitable solution, as they provide mechanical strength and flexibility with very little added weight.

They found an ideal material — a composite fabric known commercially as Dyneema, which weighs just 13 grams per square metre. This fabric was made of fibers so strong that it was used as a rope to lift the sunken cruise ship Costa Concordia from the bottom of the Mediterranean Sea. They attach the solar modules to the layers of this fabric by adding a layer of UV-curable adhesive just a few microns thick. This creates an ultra-light and mechanically robust solar structure.

“While it may seem simpler to print solar cells directly on fabric, this will limit the selection of possible fabrics or other acceptor surfaces to those that are chemically and thermally compatible with all the processing steps required to make the devices. The approach separates solar cell manufacturing from its eventual integration,” explains Saravanapavanantham. .

Outshines traditional solar cells

When testing the device, the MIT researchers discovered that it can generate 730 watts per kilogram when stand-alone and about 370 watts per kilogram when placed on high-strength Dyneema fabric, which is about 18 times more power per kilogram. than traditional solar cells

“A typical rooftop solar installation in Massachusetts is about 8,000 watts. To generate the same amount of power, our fabric photovoltaics only add about 20 kilograms (44 pounds) to the roof of a house,” he says.

They also tested the durability of their device and found that even after turning a fabric solar panel over 500 times, the cells retained more than 90 percent of their initial power generation capacity.

While solar cells are much lighter and much more flexible than conventional cells, they will need to be covered with another material to protect them from the environment. The carbon-based organic material used to make the cells can be modified in a way that interacts with moisture and oxygen in the air, degrading their performance.

“Covering these solar cells with heavy glass, as is standard with conventional silicon solar cells, will minimize the value of current progress, so the team is currently developing ultra-thin packaging solutions that will only slightly increase the weight of existing ultralight devices,” says Mwaura.

“We are working to remove as many of the non-solar-active materials as possible while maintaining the form factor and performance of these ultralight and flexible solar structures. equivalent substrates as we use them to fabricate other layers in our device. This will accelerate the translation of this technology to market,” he adds.

This research is partially funded by the MIT Energy Initiative, the US National Science Foundation, and the Canadian Natural Sciences and Engineering Research Council.


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