Earlier this week, MIT researchers announced the invention of a new kind of Low-cost, transparent, flexible, light solar cells, made out of thin graphene sheets coated with nanowires -- opening up the possibility of extremely thin, transparent solar collectors that could be applied directly to windows, roofs, and the sides of buildings in years to come.
A flexible layer of graphene, a one-atom-thick carbon material, is bonded with a polymer, to "a layer of zinc-oxide nano wires (shown in magenta), and finally a layer of a material that can extract energy from sunlight, such as quantum dots or a polymer-based material." (Credit: MIT)
The approach could lead to low-cost, transparent and flexible solar cells that could be deployed on windows, roofs or other surfaces. ...
“Currently, ITO is the material of choice for transparent electrodes,” Gradečak says, such as in the touch screens now used on smartphones. But the indium used in that compound is expensive, while graphene is made from ubiquitous carbon.
The new material, Gradečak says, may be an alternative to ITO. In addition to its lower cost, it provides other advantages, including flexibility, low weight, mechanical strength and chemical robustness. ...
Building semiconducting nanostructures directly on a pristine graphene surface without impairing its electrical and structural properties has been challenging due to graphene’s stable and inert structure, Gradečak explains. So her team used a series of polymer coatings to modify its properties, allowing them to bond a layer of zinc oxide nanowires to it, and then an overlay of a material that responds to light waves — either lead-sulfide quantum dots or a type of polymer called P3HT.
While these kind of solar cells only have a power conversion efficiency of 4.2%, much lower than photovoltaics currently on the market which typically have efficiencies of 12% to 20%, the lower cost, transparency, and flexibility give them advantages for special applications. Also, after scaling up to commercial operation, years down the road, they are expected to have certain advantages in the manufacturing process because they can be produced at temperatures below 175 degrees celsius, and applied to a wide variety of substrates such as plastic or glass, and other unconventional surfaces.
Commercial applications are expected in "a couple of years," but it is worth noting with any "proof-of-concept" stage inventions, it would not be surprising if the ramp up to commercial innovations runs into unexpected challenges, and delays. Still, one aspect of solar energy I enjoy and find inspirational is the steady stream of encouraging and optimistic news we seem to hear almost every day.
This research was supported by both National Science Foundation and the Eni-MIT Alliance Solar Frontiers Program, and used facilities provided by the MIT Center for Materials Science Engineering, so this is the kind of research that would have been on the chopping block had we elected Mitt Romney, and Paul Ryan still has these kinds of government funded research in his target sites. If you wish to support this kind of research please help vote Republicans like Paul Ryan out of the House and Senate in 2014.
For original publication in ACS, please see Graphene Cathode-Based ZnO Nanowire Hybrid Solar Cells in Nano Letters, 2012, DOI: 10.1021/nl303920b
8:35 PM PT: Hey, I'd like to shout out a special thank you to all of you have rec'd this post as you have just put me over the 31,000 accumulated total. Now, I just need another 5,000 to get on the first page of the Most Recommended Authors list under the People list.