“We grow the nanowires using a method called MBE (molecular beam epitaxy), which is not a tool that can produce materials at a high volume. However, it’s possible to produce these nanowire-based solar cells at a large scale by using an industrial-scale tool such as MOCVD (metal organic vapor deposition)”Anjan Mukherjee

Researchers from the Norwegian University of Science and Technology have devised an innovative way to make an ultra-high material efficient and inexpensive solar cell using semiconductor nanowires. Their approach uses gallium arsenide (GaAs) material through nanostructuring, potentially leading to solar cells that require a much smaller amount of the material. The method uses a vertically standing semiconductor nanowire array structure on an inexpensive Si platform to grow the nanowires.

GaAs is recognized as the most effective material for producing efficient solar cells due to its light absorption and electrical characteristics, and has been used to fabricate the solar panels used in space. However, high-quality GaAs solar cell components are expensive to produce, driving demand for new approaches that reduce its use. This study, published in the journal ACS Photonics [Mukherjee et al. ACS Photonics (2021) DOI: 10.1021/acsphotonics.1c00527], showed that positioning the material on top of a standard silicon-based solar cell could double the efficiency of standard Si solar cells and at a much lower cost.

Although GaAs solar cells are usually grown on a thick expensive GaAs substrate that does not offer much opportunity to lessen the manufacturing costs, here GaAs in a nanowire structure allowed the team to make an ultrahigh power-per-weight ratio solar cell that is over 10 times more efficient than any other solar cell.

The team realized that the most efficient and cost-effective method was to grow a dual tandem cell, with a GaAs nanowire cell on the top grown on a bottom Si cell, thus avoiding the need for a GaAs substrate. The small footprint of the nanowire structure also allows for high quality in crystals in the nanowire and in the interface with the silicon, working to improve the overall performance of the solar cell.

As researcher Anjan Mukherjee pointed out, “We grow the nanowires using a method called MBE (molecular beam epitaxy), which is not a tool that can produce materials at a high volume. However, it’s possible to produce these nanowire-based solar cells at a large scale by using an industrial-scale tool such as MOCVD (metal organic vapor deposition)”.

It is hoped the method could be enhanced by growing the nanowires on various substrates, leading to other applications. The team are investigating growing their nanowire structure on atomically thin 2D substrates such as graphene, which could lead to the development of light and flexible solar cells for use in space applications such as micro-satellites and self-powered drones.https://pubs.acs.org/doi/10.1021/acsphotonics.1c00527