Scientists at the Massachusetts Institute of Technology (MIT) Energy Initiative have developed a new flexible and transparent graphene solar cells, which can be mounted on surfaces ranging from glass to plastic to paper and tape.
Until now, developers of transparent solar cells have typically relied on expensive, brittle electrodes that tend to crack when the device is flexed.
However, graphene, a form of carbon that occurs in one-atom-thick sheets, is highly conductive, flexible, robust, and transparent.
In addition, a graphene electrode can be just one nanometer thick, a fraction as thick as the most widely used current option indium tin oxide (ITO) electrode and a far better match for the thin organic solar cell itself.
During the development, the scientists sprayed a thin layer of ethylene-vinyl acetate over the top, sticking them together like tape instead of glue to keep the layers together without any damage.
The researchers observed that their organic solar cells can be deposited on any kind of surface, including plastic, opaque paper and translucent Kapton tape.
The all-graphene devices exhibited optical transmittance of 61% across the whole visible regime and up to 69% at 550 nanometers.
The power conversion efficiency of the graphene solar cells ranged from 2.8% to 4.1%.
The researchers are now working to improve the efficiency of the graphene-based organic solar cells without sacrificing transparency.
The research was supported by the Italian energy firm Eni as part of the Eni-MIT Alliance Solar Frontiers Center. Eni is a founding member of the MIT Energy Initiative.