Taking a page from multi-junction gallium arsenide (GaAs) photovoltaics, used in high-concentrating PV, engineers and researchers at the University of California, Los Angeles, have developed a multi-layered organic photovoltaic device that converts up to 10.6 percent of light into electricity as tested by the National Renewable Energy Laboratory.
While that’s a far cry from the 33.9 efficiency record of the top-performing GaAs PV cells, they’re also significantly less costly to produce than those, as well as silicon and likely even thin-film PV.
The new cells are made of organic polymers arranged in tandem allowing them to capture multiple band gaps of sunlight. The research, published online in Nature Photonics, was supported by the National Science Foundation, the U.S Air Force Office of Scientific Research, the U.S. Office of Naval Research, the Department of Energy and NREL.
The group, led by Yang Yang, Ph.D., first broke the previous record set by Konarka in July 2011 with a 8.62 percent efficient tandem device. Then the team used a new, infrared-absorbing polymer material provided by Sumitomo Chemical of Japan, which increased its efficiency to 10.6 percent as certified by the U.S. Department of Energy's National Renewable Energy Laboratory.
That’s coming close to the mark of thin-film PV like First Solar and Abound Solar, both of which are on a path to produce modules that at are more than 14 percent efficient at converting sunlight into electricity and are producing commercial PV modules that are around 11 to 12 percent efficient.
But so far UCLA’s devices are small. The group is looking for partners that will scale the technology up to the size of a PV module.
“At 10 percent [across a module] it will be ready for commercialization,” Yang said.
Organic PV generally is considered for flexible applications like clothing that can charge a smartphone or perhaps power LEDs for a sign. But with the higher conversion efficiencies it could be used in other applications.
“We look far beyond clothes. Our target—my dream—is to have organic photovoltaics everywhere. I think this tech has the potential to revolutionize the solar industry,” Yang said.
The technology could even take on silicon PV eventually.
Organic PV also has suffered from a shorter lifespan than other PV types. The organic materials in the cells are less stable and break down more rapidly than in other modules. A challenge the technologies will have to overcome.
At this point, Yang expects that the devices could last about seven years in the field, maybe even up to 10 years.