Taking their cue from the humble leaf, researchers have used microscopic folds on the surface of photovoltaic material to significantly increase the power output of flexible, low-cost solar cells.
The team, led by scientists from Princeton University, reported online April 22 in the journal Nature Photonics that the folds resulted in a 47 percent increase in electricity generation. Yueh-Lin (Lynn) Loo, the principal investigator, said the finely calibrated folds on the surface of the panels channel light waves and increase the photovoltaic material’s exposure to light.
“On a flat surface, the light either is absorbed or it bounces back,” said Loo, a professor of chemical and biological engineering at Princeton. “By adding these curves, we create a kind of wave guide. And that leads to a greater chance of the light’s being absorbed.”
The research team’s work involves photovoltaic systems made of relatively cheap plastic. Current solar panels are typically made of silicon, which is both more brittle and more expensive than plastics. So far, plastic panels have not been practical for widespread use because their energy production has been too low. But researchers have been working to increase that efficiency with the goal of creating a cheap, tough and flexible source of solar power.
If researchers can increase the plastic panels’ efficiency, the material could produce power from an array of surfaces from inserts in window panels to overlays on exterior walls or backpacks.
“It is flexible, bendable, light weight and low cost,” Loo said.
In most cases, researchers have focused on increasing the efficiency of the plastic photovoltaic material itself. Recent developments have been promising: a team from UCLA recently announced a system with a 10.6 percent efficiency. That approaches the 10 to 15 percent level seen as the target for commercial development.