Researchers at the University of New South Wales (UNSW) Sydney claim they have increased the efficiency of solar technology by utilizing the concept of singlet fission, increasing the theoretical efficiency limit of silicon cells to approximately 45%.

Singlet fission refers to a process where a single light particle, a photon, is split into two packets of energy, doubling the output of solar energy technologies.

The research team, known as Omega Silicon, published their findings in ACS Publications. The findings demonstrate how singlet fission works on an organic material called Dipyrrolonaphthyridinedione (DNPD), which could be mass-produced in the future for use in solar panels.

Ben Carwithen, a postdoctoral researcher at UNSW’s School of Chemistry, stated that a considerable amount of the energy from sunlight in solar cells is wasted as heat, which is itself a form of energy. The Omega Silicon team is exploring ways to convert wasted energy into additional electricity.

How the Technology Works

A majority of solar panels today are made from silicon, a material that is affordable and reliable. However, this technology suffers from some limitations. The best commercial silicon cells currently convert only about 27% of sunlight into electricity, with the technology’s theoretical limit capping at approximately 29.4%.

Ned Ekins-Daukes, project lead and head of UNSW’s School of Photovoltaic and Renewable Energy Engineering, stated that introducing singlet fission into a silicon solar panel will increase its efficiency as the process enables a molecular layer to supply the panel with additional current.

As part of the singlet fission process, researchers added a layer of DNPD over a conventional silicon solar cell. When sunlight hits the DNPD layer, a single high-energy photon produces two lower-energy excitations. This means the solar cell can produce two usable energy packets instead of just one.

UNSW said finding the right material has been a challenge until now. Other teams working to address this challenge earlier had used a compound called tetracene. This material performed well in labs but degraded too quickly in air and moisture for practical use.

Omega Silicon said its research demonstrates how DNPD can perform equally well while maintaining stability under real-world outdoor conditions.

“We have shown that you can interface silicon with this stable material, which undergoes singlet fission, and then injects extra electrical charge,” said Carwithen.

He added that although these findings are an early step, they are the first demonstrations that can work in a realistic system.

Adding to Previous Work

According to UNSW, Omega Silicon’s discovery builds on over a decade-long research effort led by Tim Schmidt, head of UNSW’s School of Chemistry. His team had utilized magnetic fields to reveal a key pathway to the singlet fission process.

“We used magnetic fields to manipulate the emitted light and reveal how singlet fission occurs. This had not been done before,” said Schmidt.

Researchers leveraged their understanding of the underlying physics from Schmidt’s earlier research to design improved materials and layer structures, enhancing the effectiveness of singlet fission.

Schmidt explained, “Different colors of light carry different energies. Blue light has more energy, but most of that gets lost as heat in a normal solar cell. With singlet fission, that excess energy can be turned into usable electricity instead.”

This research is part of a broader initiative across Australia to increase the efficiency and affordability of solar energy.

Earlier, a team of researchers from UNSW and the Chinese solar module manufacturer LONGi discovered that the rear side of TOPCon cells, particularly the silicon nitride layer, is prone to chemical degradation when exposed to sodium-based salts, leading to a significant loss of open-circuit voltage.