Thinking small for solar
- PDF / 418,594 Bytes
- 2 Pages / 585 x 783 pts Page_size
- 7 Downloads / 193 Views
•
Energy Sector Analysis
Organic photovoltaic cells that use small molecules post record-high efficiencies, prompting materials researchers to take a new look.
Thinking small for solar By Corinna Wu Feature Editor Hideyuki Murata
O
n rooftops all over the world, silicon solar panels are harvesting sunlight and converting it into gigawatts of electricity. But now, many groups are hard at work developing solar technology that eschews silicon and other inorganic materials altogether. Organic photovoltaics (OPV), which uses organic materials such as polymers as the active component, follows on the heels of first-generation crystalline silicon and second-generation thin-film PV. OPV promises to be lightweight, flexible, and cheaper to manufacture. Its unique properties also open a range of applications not possible with inorganic solar materials. Recently, new approaches to making OPV that use small organic molecules as the light-harvesting ingredient have posted some remarkable successes. Until now, it was unclear whether small-molecule OPV had the potential shown by polymer OPV technologies. But power conversion efficiencies reaching 10%—near that of amorphous silicon—have encouraged companies and academic groups to plunge forward with their small-molecule OPV research. Organic PV is attractive because the overall cost of the electrical power generated—expressed as lifetime multiplied by efficiency/manufacturing cost—can be extrapolated to become much lower than that of silicon or thin-film PV. The critical price point is much less than $1/W, which is where “PV breaks even with some of the other conventional technologies that are used for power generation—namely, the burning of some kind of fossil fuel,” said Bernard Kippelen, director of the Center for Organic Photonics and Electronics at the Georgia Institute of Technology. The production cost of today’s silicon PV technology is around $1–2/W, Kippelen said, but the price of the raw material—pure, electronic-grade silicon—makes up a substantial portion of the cost of the device. “You can’t go much beyond the cost of the materials that are needed to fabricate the cell unless someone comes up with a new process where you have a lowcost way to produce high-quality silicon,” he said. “That would really require a breakthrough.” The inorganic materials used in thin-film PV, such as cadmium telluride, have similar limitations for breakthrough raw material cost reductions. On the other hand, organic molecules are typically cheaper Hideyuki Murata, Japan Advanced Institute of Science and Technology Corinna Wu, [email protected]
194
MRS BULLETIN
•
VOLUME 37 • MARCH 2012
•
www.mrs.org/bulletin • Energy Quarterly
and more abundant. The layers of materials in OPV can also be much thinner, so less material is needed. If a 100-nm-thick layer can absorb sunlight effectively, the amount of material that coats 10 m2 would not be more than 1–2 grams, Kippelen said. OPV can also be manufactured at low temperatures, which reduces the energy needed and allows for the use of plasti
Data Loading...
