The United States Patent Office has approved IBM’s patent application for a method of using graphene in solar cells. US patent number 8293607 describes a method to decrease the electrical resistance of graphene sheets, for use as a transparent electrode in photovoltaics.
Transparent electrodes on solar cells serve as a route for extracting the electricity generated by sunlight, without absorbing the light before it gets to the active material of the cell. Indium tin oxide (ITO) is the material of choice for modern solar cells, as it is abundant in nature and can be deposited using well-established fabrication techniques. The methods of fabrication are expensive though, and ITO is brittle, making it unsuitable for flexible solar cells. Enter graphene, an excellent conductor with a high transparency, which is, in addition, highly flexible. In its natural form, graphene has a low electrical resistance compared to most other materials, making it ideal for moving around electricity. IBM researchers use the fact that the resistance of graphene can be reduced even further by chemical means to produce a highly conductive transparent electrode for a solar cell.
This is one of a series of ingenious patents by IBM that use graphene for advanced electronic or opto-electronic components. The company has a large R&D sector devoted to graphene and invests heavily in graphene devices which are close to the end user. Its continued research excellence and perpetually rising stock make IBM an excellent choice for the graphene investor.
