Ultra-Slim Solar Cells
Traditional silicon solar cells are extremely fragile and have to encased in glass and packaged in heavy, thick aluminum framing to support them. This adds significantly to the production costs and also limits where and how they can be deployed.
In December 19, 2022, in a research funded by Eni S.p.A. through the MIT Energy Initiative, the U.S. National Science Foundation, and the Natural Sciences and Engineering Research Council of Canada, scientists at MIT announced that they had developed ultralight fabric solar cells that can quickly and easily turn any surface into a power source.
These solar cells are extremely thin and flexible, making them easy to install on a variety of surfaces. They can be worn as a power-generating fabric or quickly deployed in emergencies. These cells are significantly lighter than traditional solar panels, but are able to generate 18 times more power per kilogram. They are made using semiconducting inks and printed using processes that can be scaled for large-area manufacturing.
In addition to being able to be attached to fixed surfaces, these solar cells can also be laminated onto various objects, such as the sails of boats, tents and tarps used in disaster recovery, and the wings of drones. Their lightweight and easy-to-install nature make them suitable for integration into built environments.
In 2016, researchers at the ONE Lab developed a method for creating thin-film solar cells using printable, ink-based materials and scalable fabrication techniques. These solar cells were made using nanomaterials in the form of electronic inks that are coated onto a 3 micron thick, releasable substrate using a slot-die coater. An electrode is then added to the structure using screen printing to complete the solar module, which is around 15 microns thick.
However, these thin, freestanding solar modules are prone to tearing and are difficult to handle, so the researchers sought out a lightweight, flexible, and high-strength substrate to adhere them to. They found that composite fabrics, such as Dyneema, provided the ideal solution as they offer both flexibility and mechanical resilience with minimal added weight. By using a layer of UV-curable glue, the solar modules can be attached to sheets of this fabric, resulting in an ultra-light and mechanically robust solar structure.
When tested, the researchers found it could generate 730W of power per kilogram when freestanding and about 370 watts-per-kilogram if deployed on the high-strength Dyneema fabric, which is about 18 times more power-per-kilogram than conventional solar cells.
The researchers tested the durability of their devices and found that the cells still retained more than 90% of their initial power generation capabilities even after being rolled and unrolled more than 500 times.
Although the solar cells are much lighter and more flexible than traditional cells, they still need to be encased in a protective material due to their susceptibility to deterioration when exposed to the environment. The carbon-based organic material used to make the cells can be modified when interacting with moisture and oxygen in the air, which can negatively impact their performance.
According to one of the researchers,
“Encasing these solar cells in heavy glass, as is standard with the traditional silicon solar cells, would minimize the value of the present advancement, so the team is currently developing ultrathin packaging solutions that would only fractionally increase the weight of the present ultralight devices.
“We are working to remove as much of the non-solar-active material as possible while still retaining the form factor and performance of these ultralight and flexible solar structures. For example, we know the manufacturing process can be further streamlined by printing the releasable substrates, equivalent to the process we use to fabricate the other layers in our device. This would accelerate the translation of this technology to the market,” he adds.
The full research paper can be assessed at this link.