Scientists and technologists around the world are beginning to see the promising possibilities of graphene to build cheap, lightweight conductors for everything from solar-power systems to computer touchscreens. The simple, flexible nature of the material could make it possible—a flat monolayer of carbon atoms packed into a two-dimensional honeycomb lattice that can be used as a basic building block to make multi-dimensional forms.
As a material, graphene is only one atom thick, a virtually transparent network of carbon conductors that can be wrapped around most anything, rolled into nanotubes or stacked into three-dimensional forms. Most importantly, for its size and weight, graphene has an off-the-charts ability to conduct electrons.
While scientists have known about graphene for decades, the carbon-sheet form was only isolated in 2004. Since then, scientists and engineers have been addressing the difficulties of manufacturing sheets in large sizes at the quality required for commercial applications.
One of the latest breakthroughs is using graphene to make organic photovoltaic (OPV) cells. In the June issue of the American Chemical Society’s “Nano,” a team of researchers at the University of Southern California (USC) proposed a new means of manufacturing OPV cells. The technique described in the article showed progress toward an OPV cell design that has significant advantages, particularly in the area of physical flexibility.
A critical aspect of any OPV photo-electronic device is a transparent conductive electrode, through which light can couple with active materials to create electricity. It promises to be a way to achieve low-cost energy production because of the ease of manufacture and compatibility with flexible substrates.
The USC team has produced graphene--polymer sheets in sizes up to 150 square centimeters that can be used to create arrays of flexible OPV cells. While OPV converts solar radiation into electricity, it is not as efficient as today’s silicon cell. But what graphene-based OPV lacks in efficiency can potentially be offset by a much lower price for production and ubiquitous physical flexibility. It may be possible to run printing-like presses to lay down OPV cells on a variety of substrates, including films and fabrics.
We could see the day when transparent graphene-based solar cells are applied to virtually any surface— windows, siding, drapes, even clothing—to generate electricity for electronic devices, automobiles, etc. For example, it could be imprinted on a jogger’s outfit to power a mobile device.