A team of scientists from Pennsylvania State University (Penn State) has found that nanoparticles boost the efficiency of solar cells not because of the up-conversion but due to enhanced light scattering.

The scientists said that this light scattering process boosted efficiency in the solar devices they created. Scientists have proposed that tapping into this could push solar cell efficiency past its theoretical ceiling, the Shockley-Queisser (SQ) limit, which is around 30% for single-junction solar cells powered by sunlight.

The usual method involves adding up-conversion nanoparticles to the materials used in the solar devices. Up-conversion materials allow solar cells to harvest energy from a wider spectrum of light than normally possible. Adding nanoparticles is like adding millions of small mirrors inside a solar cell. The light traveling through the device hits the nanoparticles and scatters, potentially hitting other nanoparticles, reflecting many times within the device, and providing a noticeable photocurrent enhancement.

“We were focused initially on up-converting infrared light to the visible spectrum for absorption and energy conversion by perovskite, but the data from our PennState colleagues indicated this was not a significant process. Subsequently, we provided undoped nanocrystals that do not give optical up-conversion, and they were just as effective in enhancing the energy conversion efficiency,” said Jim Piper, co-author and emeritus professor at Macquarie University, Australia.

Adding the nanoparticles boosted the efficiency of perovskite solar cells by 1% in the study, the scientists reported in the journal ACS Energy Letters. Changing the shape, size, and distribution of nanoparticles within these devices could further lead to even more photocurrent enhancement and higher efficiencies.

“It could be the future research direction based on ideas from this research,” said Shashank Priya, associate vice president for research and professor of materials science and engineering at Penn State.

Last month, researchers from Swansea university and Tata Steel, UK, found that perovskite solar cells could be printed on steel atop buildings.

Earlier, Fraunhofer researchers claimed to have achieved a record efficiency of 47.6% for a four-junction solar cell.