Solar cells one-fiftieth of a human hair created
4 Apr 2016 by Evoluted New Media
MIT scientists have produced solar cells so small and light they can be placed on a soap bubble.
MIT scientists have produced solar cells so small and light they can be placed on a soap bubble.
The researchers were able to do this by making the solar cell, supporting substrate and protective overcoat all in one process. This new approach to construction means the substrate is not touched during construction eliminating any possibility of contamination, which would decrease performance.
Professor Vladimir Bulovi?, one of the authors of the study from MIT, said: “The innovative step is the realisation that you can grow the substrate at the same time as you grow the device.”
Parylene – a flexible polymer – was used as both substrate and overcoating. Dibutyl phthalate (DBP), an organic material, was used as the primary light-absorbing layer. The process took place at room temperature, in a vacuum, without the use of any solvents, using chemical vapour deposition (CVD). CVD involves monomers of the polymer coating being introduced into a vacuum to form polymers on the surface of the substrate. This is a marked difference from usual solar cell manufacturing which requires both high temperatures and solvents.
The MIT scientists stress the materials used were examples and the technique is the most important part of this finding. To show how thin the solar cells produced were, researchers placed them on top of a soap bubble, without the bubble bursting. Parylene films with thicknesses up to 80 microns could be deposited easily using commercial equipment, according to the researchers.
Annie Wang, also from MIT said: “We put our carrier (glass) in a vacuum system; we deposited everything else on top of it, and then peeled the whole thing off.” The final solar cells measured one-fiftieth of a human hair and were a thousand times thinner than conventional solar cells, but converted sunlight into electricity just as efficiently.
As the solar cells are so light, they have a very high power-to-weight ratio of six watts per gram. This is almost 400 times higher than conventional solar cells which can produce 15 watts per kilogram.
Bulovi? said: “We have a proof-of-concept that works. The next question is, “How many miracles does it take to make it scalable? We think it’s a lot of hard work ahead, but likely no miracles needed.”
The research was published in Organic Electronics.
