Researchers from Princeton University claim to have found a simple and economical way to nearly triple the efficiency of photovoltaics.
Working with organic solar cells – flexible solar cells made from plastic – the researchers were able to increase the efficiency of the devices by 175% by using a nanostructured "sandwich" of metal and plastic to overcome two primary challenges that cause solar cells to lose energy: light reflecting from the cell, and the inability to fully capture light that enters the cell.
The sandwich — called a subwavelength plasmonic cavity — has the ability to dampen reflection and trap light. The new technique allowed the research team to create a solar cell that only reflects about 4% of light and absorbs as much as 96%. It demonstrates 52% higher efficiency in converting direct light to electrical energy than a conventional solar cell.
The structure achieves even more efficiency for light that strikes the solar cell at large angles, which occurs on cloudy days or when the cell is not directly facing the sun. By capturing these angled rays, the new structure boosts efficiency by an additional 81%, leading to the 175% total increase.
According to professor of engineering Stephen Chou, who led the research, the system is ready for commercial use although, as with any new product, there will be a transition period in moving from the lab to mass production.
He also added that the same technology could also be used to increase the efficiency of conventional inorganic solar collectors, such as standard silicon solar panels, although research with such devices has yet to be completed.
The researchers said the plasmonic cavity solar cells can be manufactured cost-effectively in wallpaper-size sheets. Chou's lab used "nanoimprint," a low-cost nanofabrication technique Chou invented 16 years ago, which embosses nanostructures over a large area, like printing a newspaper.
When used to boost the efficiency of traditional silicon panels the technology could reduce the thickness of the silicon used by a thousand-fold, which could substantially decrease manufacturing costs and allow the panels to become more flexible.
Chou said the team plans further experiments and expects to increase the efficiency of the system as they refine the technology.
The findings of the research were originally published in the journal Optics Express.