Inroads into expanding the capabilities of solar cells continue to grow every day.
The efficiency of all solar panel designs could improve by up to 22 percent by covering the surface with aluminum studs that bend and trap light inside the absorbing layer.
At the microscopic level, the studs make the surface of the solar panels look similar to interlocking building bricks, said researches at the Imperial College London with international collaborators in Belgium, China and Japan.
“In recent years both the efficiency and cost of commercial solar panels have improved but they remain expensive compared to fossil fuels. As the absorbing material alone can make up half the cost of a solar panel our aim has been to reduce to a minimum the amount that is needed,” said lead author Dr. Nicholas Hylton from the Department of Physics at Imperial College London.
“The success of our technology, in combination with modern anti-reflection coatings, will take us a long way down the path toward highly efficient and thin solar cells that could be available at a competitive price,” Hylton said.
The key to understanding these new results is in the way the internal structures of these metals interact with light.
Hylton and his colleagues attached rows of aluminum cylinders just 100 nanometers across to the top of the solar panel, where they interact with passing light, causing individual light rays to change course. More energy ends up extracted from the light as the rays become effectively trapped inside the solar panel and travel for longer distances through its absorbing layer.
In the past, scientists have tried to achieve the light bending effect using silver and gold studs because those materials strongly interact with light, however these precious metals actually reduce the efficiency as they absorb some of the light before it enters the solar panel.
“The key to understanding these new results is in the way the internal structures of these metals interact with light,” Hylton said. “Gold and silver both have a strong effect on passing light rays, which can penetrate into the tiny studs and be absorbed, whereas aluminum has a different interaction and merely bends and scatters light as it travels past them into the solar cells.”
An additional advantage to this solution is that aluminum is less costly and far more abundant than silver and gold.
The future success of this technology opens up the possibility of making flexible solar panels that could be applied to any flat or curved surface, which could power anything from domestic appliances to portable electronics like laptops.