Looking for a way to make solar panels more efficient? Why not try putting a dent in them?
However this isn’t something you could do with your own home solar panel by way of a ladder and a hammer, though. Instead, the research shows that it’s possible to squeeze extra power out of solar cells by deforming the tiny p-type and n-type crystals in photovoltaic semiconductors.
Most commercial solar panels are made up of two layers, which create a junction at the boundary where the positively charged p-type and negatively-charged n-type semiconductors meet. When the solar cell absorbs light, this junction splits the photo-excited carriers in opposite directions, thereby generating current and voltage.
But while this junction is crucial for producing electricity, it also comes with a limit — called the Shockley-Queisser limit — which stops any more than 33.7 percent of the power in sunlight being transformed into electricity.
For their demonstration, the researchers at the United Kingdom’s University of Warwick used conductive tips to force semiconductors into a device called a nano-indenter, which deformed the individual crystals.
By making the semiconductors non-symmetrical, they were able to create something called the “bulk photovoltaic effect,” another way to collect charge. Combining these two approaches resulted in improved efficiency of solar cells and the chance to generate more electrical energy from sunlight.
“This flexo-photovoltaic effect is a new effect,” It shows that by engineering the strain applied, any semiconductor can be transformed in a photovoltaic generator without a need [for] chemical doping or any other processing.
They have yet to evaluate in detail how effective is this effect. But in principle there is nothing to prevent combining the two effects, the classical harvesting using p-n junctions and the present flexo-PV effect.”
The team has filed a patent application to lay claim to their work.