Want to take a solar cell to a remote location so you can easily charge your flashlight or your cell phone? No problem: fold it up and slip it into your back pocket.
That’s the promise of a new technology developed by MIT professors Karen Gleason ‘82, SM ‘82, and Vladimir Bulovi, working with graduate student Miles Barr and several other students and postdocs. They have developed a way to print a solar cell onto almost any material, including flexible plastics, cloth, and paper. In tests, the new photovoltaic material showed virtually no loss of performance after being folded and unfolded 1,000 times.
In the United States, a solar cell’s supporting structure, the installation process, and the substrate (usually glass) that holds the photovoltaic material can cost up to twice as much as the active components of the cell itself. Printing solar cells directly onto inexpensive materials and then just fastening them to a wall for support could drastically reduce the costs of solar installations, which could be incorporated into window shades or wallpaper. Today, most commercial photovoltaic cells are produced using very high temperatures. The printing process developed by the MIT team requires temperatures of less than 120 °C, making it possible to use untreated cloth, plastic, or even ordinary paper as a substrate. The process also has an advantage over recently developed methods that print solar cells by using liquids to deposit organic materials onto a substrate. While printing with liquids can leave gaps on rough surfaces, hindering the device’s electrical conductivity, Gleason and Bulovi’s process uses vapors instead of liquids, producing a more uniform layer, even on rough surfaces like paper. And paper costs a thousandth as much as glass for a given area, the researchers say.
Because paper and plastic are so much lighter than glass or other substrate materials, Bulovi says, “we think we can fabricate scalable solar cells that can reach record-high watts-per-kilogram performance.”
To create an array of photovoltaic cells using the new method, five successive layers of material are deposited onto a sheet of paper (or cloth or plastic) in a vacuum chamber; stencil-like masks are used to form the necessary patterns. The vapor deposition process, similar to that used to make the silvery lining in potato chip bags, is quite adaptable to large-scale manufacturing.
The paper-printed solar cells currently turn just 1 percent of incoming sunlight into electricity, but the researchers believe their efficiency can be increased significantly by fine-tuning the materials. Even at the present level, Bulovi says, the cells are “good enough to power a small electric gizmo.”
These weird virtual creatures evolve their bodies to solve problems
They show how intelligence and body plans are closely linked—and could unlock AI for robots.
Surgeons have successfully tested a pig’s kidney in a human patient
The test, in a brain-dead patient, was very short but represents a milestone in the long quest to use animal organs in human transplants.
Is everything in the world a little bit conscious?
The idea that consciousness is widespread is attractive to many for intellectual and, perhaps, also emotional
reasons. But can it be tested? Surprisingly, perhaps it can.
We reviewed three at-home covid tests. The results were mixed.
Over-the-counter coronavirus tests are finally available in the US. Some are more accurate and easier to use than others.
Get the latest updates from
MIT Technology Review
Discover special offers, top stories, upcoming events, and more.