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Solar Cell Polymers with Multiplied Electrical Output
(Please note, material from Brookhaven National Laboratory. Copyright concerns are nil.)
http://www.bnl.gov/newsroom/news.php?a=11691
[font face=Serif][font size=5]Solar Cell Polymers with Multiplied Electrical Output[/font]
[font size=4]New family of materials produces "twin" electrical charges on single molecules, potentially paving the way for easy manufacture of more efficient solar devices[/font]
January 12, 2015
[font size=3]UPTON, NY — One challenge in improving the efficiency of solar cells is that some of the absorbed light energy is lost as heat. So scientists have been looking to design materials that can convert more of that energy into useful electricity. Now a team from the U.S. Department of Energy's Brookhaven National Laboratory and Columbia University has paired up polymers that recover some of that lost energy by producing two electrical charge carriers per unit of light instead of the usual one.
"Critically, we show how this multiplication process can be made efficient on a single molecular polymer chain," said physicist Matthew Sfeir, who led the research at Brookhaven Lab's Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility. Having the two charges on the same molecule means the light-absorbing, energy-producing materials don't have to be arrayed as perfect crystals to produce extra electrical charges. Instead, the self-contained materials work efficiently when dissolved in liquids, which opens the way for a wide range of industrial scale manufacturing processes, including "printing" solar-energy-producing material like ink.
The research is published as an Advance Online Publication in Nature Materials, January 12, 2015.
The concept of producing two charges from one unit of light is called "singlet fission." (Think of the fission that splits a single biological cell into two when cells multiply.) Devices based on this multiplication concept have the potential to break through the upper limit on the efficiency of so-called single junction solar cells, which is currently around 34 percent. The challenges go beyond doubling the electrical output of the solar cell materials, because these materials must be incorporated into actual current-producing devices. But the hope is that the more-efficient current-generating materials could be added on to existing solar cell materials and device structures, or spark new types of solar cell designs.
Most singlet fission materials explored so far result in twin charge carriers being produced on separate molecules. These only work well when the material is in a crystalline film with long-range order, where strong coupling results in an additional charge being produced on a neighboring molecule. Producing such high quality crystalline films and integrating them with solar cell manufacturing complicates the process.
Producing the twin charges on a single polymer molecule, in contrast, results in a material that's compatible with a much wider variety of industrial processes.
…[/font][/font]
[font size=4]New family of materials produces "twin" electrical charges on single molecules, potentially paving the way for easy manufacture of more efficient solar devices[/font]
January 12, 2015
[font size=3]UPTON, NY — One challenge in improving the efficiency of solar cells is that some of the absorbed light energy is lost as heat. So scientists have been looking to design materials that can convert more of that energy into useful electricity. Now a team from the U.S. Department of Energy's Brookhaven National Laboratory and Columbia University has paired up polymers that recover some of that lost energy by producing two electrical charge carriers per unit of light instead of the usual one.
"Critically, we show how this multiplication process can be made efficient on a single molecular polymer chain," said physicist Matthew Sfeir, who led the research at Brookhaven Lab's Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility. Having the two charges on the same molecule means the light-absorbing, energy-producing materials don't have to be arrayed as perfect crystals to produce extra electrical charges. Instead, the self-contained materials work efficiently when dissolved in liquids, which opens the way for a wide range of industrial scale manufacturing processes, including "printing" solar-energy-producing material like ink.
The research is published as an Advance Online Publication in Nature Materials, January 12, 2015.
The concept of producing two charges from one unit of light is called "singlet fission." (Think of the fission that splits a single biological cell into two when cells multiply.) Devices based on this multiplication concept have the potential to break through the upper limit on the efficiency of so-called single junction solar cells, which is currently around 34 percent. The challenges go beyond doubling the electrical output of the solar cell materials, because these materials must be incorporated into actual current-producing devices. But the hope is that the more-efficient current-generating materials could be added on to existing solar cell materials and device structures, or spark new types of solar cell designs.
Most singlet fission materials explored so far result in twin charge carriers being produced on separate molecules. These only work well when the material is in a crystalline film with long-range order, where strong coupling results in an additional charge being produced on a neighboring molecule. Producing such high quality crystalline films and integrating them with solar cell manufacturing complicates the process.
Producing the twin charges on a single polymer molecule, in contrast, results in a material that's compatible with a much wider variety of industrial processes.
…[/font][/font]
