Why are efficient and affordable solar cells so highly coveted?
Volume. The amount of solar energy lighting up Earth’s land mass
every year is nearly 3,000 times the total amount of annual
human energy use. But to compete with energy from fossil fuels,
photovoltaic devices must convert sunlight to electricity with a
certain measure of efficiency. For polymer-based organic
photovoltaic cells, which are far less expensive to manufacture
than silicon-based solar cells, scientists have long believed
that the key to high efficiencies rests in the purity of the
polymer/organic cell’s two domains – acceptor and donor. Now,
however, an alternate and possibly easier route forward has been
shown. Working at Berkeley Lab’s Advanced Light Source (ALS), a
premier source of X-ray and ultraviolet light beams for
research, an international team of scientists found that for
highly efficient polymer/organic photovoltaic cells, size
matters. “We’ve shown that impure domains if made sufficiently
small can also lead to improved p