Thinnest, lightest solar cell ever can sit on a soap bubble without popping it
MIT has demonstrated a solar cell technology that could be placed on almost any surface including our clothing, smartphones, even pieces of paper or helium balloons without being noticed.
MIT says it is the thinnest, lightest solar cell ever produced and it could be the key to a future where any surface could be used to generate clean energy.
MIT professor Vladimir Bulović, associate dean for innovation says that they were able to achieve this breakthrough by making the solar cell, the substrate and its protective overcoating all in one process. The whole process takes place in a vacuum chamber to prevent dust and other contaminants from settling on the surface.
The substrate and overcoating in this prototype are made from a common flexible polymer called parylene and the light-absorbing layer is made from an organic material called DBP. The solar cell and substrate are "grown" using a technique called vapor deposition. This allows the solar cell to be built without harsh chemical solvents or high temperatures.
The device that they made is just a proof-of-concept and therefore not very efficient, but it's so lightweight it has the highest power-to-weight ratio ever achieved. A typical silicon-based solar cell might produce about 15 watts per kilogram while this new solar cell produces 6 watts per gram, about 400 times the output.
MIT says, "The final ultra-thin, flexible solar cells, including substrate and overcoating, are just one-fiftieth of the thickness of a human hair and one-thousandth of the thickness of equivalent cells on glass substrates — about two micrometers thick — yet they convert sunlight into electricity just as efficiently as their glass-based counterparts."
The researchers stress that other materials could be used to make the solar cell, it's the manufacturing process that is the real breakthrough. In the future this method could be used to make solar cells so light that they'd be undetectable on your shirt, notebook or any existing surfaces.
To demonstrate just how flexible and lightweight the solar cell is the team deposited a working cell on a soap bubble without popping it. While this extreme thinness might be impractical in real-world applications -- it could be blown away -- the parylene film could be scaled up in thickness to 80 microns and be deposited easily with commercial equipment while still being compatible with the manufacturing process they used.
The technology still needs a lot of work before commercial manufacturing could be considered, but the researchers think this breakthrough signals great things for solar technology in the future.