UNSW Sydney says its engineers have set a world record for the performance of solar cells made from antimony chalcogenide, an emerging photovoltaic material, marking a significant advance in manufacturing for next-generation solar technology.
In a news release, the university said its research team achieved a certified efficiency of 10.7% – which it claims is the highest independently verified performance worldwide for this material – earning antimony chalcogenide its first listing in the international Solar Cell Efficiency Tables.
The breakthrough, published in Nature Energy, also uncovered the chemical mechanism underlying the hydrothermal deposition process used in manufacturing the material, potentially accelerating its future development.
Professor Xiaojing Hao, from UNSW’s School of Photovoltaic and Renewable Energy Engineering, said: “The next generation of technology for solar panels is tandem cells, where two or more solar cells are stacked to absorb different parts of sunlight. Antimony chalcogenide is a very positive top cell candidate due to its distinct properties, and we need more options to partner with silicon cells.”
According to the researchers, antimony chalcogenide offers several advantages for manufacturing. It is composed of abundant, low-cost elements, is inherently stable as an inorganic material, and has a high light absorption coefficient, requiring only a 300-nanometre-thick layer to capture sunlight effectively. It can also be deposited at low temperatures, supporting energy-efficient and scalable production.
The UNSW team identified a key obstacle to efficiency in earlier versions of the material: uneven distribution of sulfur and selenium created an “energy barrier” that limited the flow of electrical charge.
Dr Chen Qian, first author of the paper, explained: “When the distribution of elements inside the cell is more even, charge moves more easily through the absorber rather than being trapped, which means more sunlight is converted into electricity.”
The researchers addressed the issue by adding a small amount of sodium sulfide during manufacturing, which stabilises chemical reactions in the solar-absorbing layer. Laboratory tests at UNSW reached 11.02% efficiency, with CSIRO independently certifying 10.7%.
Dr Qian noted further improvements are possible: “In the next few years we will continue to reduce defects via chemical passivation. We believe it is achievable to increase efficiency to 12% by addressing these challenges one step at a time.”
Beyond tandem panels, antimony chalcogenide’s ultrathin, semi-transparent properties and strong indoor light performance make it suitable for applications such as see-through solar windows, self-powered sensors, and solar-powered electronic devices. Sydney Solar, a UNSW spinout, is already working to scale production of solar “stickers” for windows.
Dr Jialiang Huang, part of the research team, said the findings represent an important milestone in sustainable solar manufacturing: “By understanding the chemistry behind these cells, we can manufacture more efficient, cost-effective, and durable solar technology for a range of applications.”
