19 Apr 2013:
New Solar Cell Process
Achieves Record Efficiency, MIT Says
Researchers at the Massachusetts Institute of Technology (MIT) say they have achieved a major breakthrough in the conversion of sunlight into electricity
, surpassing what was long believed to be an absolute limit to the efficiency of solar cell devices. While the process used in the typical photovoltaic (PV) cell process knocks loose one electron inside the PV material to produce an electrical current — but wastes any excess energy carried by a photon — a new process described in the journal Science
utilizes that extra energy to produce two electrons. That exploits so-called singlet exciton fission and makes the process far more efficient, creating more electrical energy. An exciton is the excited state of a molecule after absorbing energy. While the material used in the organic solar cell, known as pentacene, was previously known to produce two so-called excitons from one photon, researchers say this is the first time anyone has demonstrated the principle within a photovoltaic device. While the typical solar panel achieves efficiencies no greater than 25 percent, the scientists believe this process can be utilized to achieve efficiencies of more than 30 percent.
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Tribal people and ranchers join together to stop a project that would haul coal across their Montana land. Watch the video.
is now available for mobile devices at e360.yale.edu/mobile
An aerial view of why Europe’s per capita carbon emissions are less than 50 percent of those in the U.S. View the photos.
Ugandan scientists monitor the impact of climate change on one of Africa’s most diverse forests and its extraordinary wildlife. Learn more.
video series looks at the staggering amount of food wasted in the U.S. – a problem with major human and environmental costs. Watch the video.
video goes onto the front lines with Colorado firefighters confronting deadly blazes fueled by a hotter, drier climate. Watch the video.
A three-part series Tainted Harvest
looks at the soil pollution crisis in China, the threat it poses to the food supply, and the complexity of any cleanup. Read the series.