Researchers at the University of New South Wales, led by Professor Xiaojing Hao from the School of Photovoltaic and Renewable Energy Engineering, have reported a certified efficiency milestone for antimony chalcogenide solar cells, a photovoltaic material that has been under steady investigation as a candidate for next generation solar technologies. The team achieved an independently verified power conversion efficiency of 10.7 percent, the highest confirmed value for this material to date, marking its first inclusion in the international Solar Cell Efficiency Tables.
Qian, C., Sun, K., Huang, J., Yang, J., Cong, J., He, M., Li, Z., Feng, Z., Liu, X., Tang, R., Green, M., Chen, T., & Hao, X. (2026). Regulation of hydrothermal reaction kinetics with sodium sulfide for certified 10.7% efficiency Sb2(S,Se)3 solar cells. Nature Energy. https://doi.org/10.1038/s41560-025-01952-0
Antimony chalcogenide, typically formulated as Sb₂(S,Se)₃, has attracted interest as a potential top cell material for tandem photovoltaic devices, where multiple absorber layers are stacked to capture different portions of the solar spectrum. In this configuration, a wide bandgap material is paired with conventional silicon to increase overall energy yield without requiring a complete departure from existing manufacturing infrastructure. While a number of materials are being explored globally for this role, antimony chalcogenide stands out for combining relatively low material cost with inorganic stability.
Professor Xiaojing Hao from University of New South Wales stated,
“We believe an achievable aim is to increase the efficiency up to 12% in the near future by addressing the challenges that still remain, one step at a time.”
One of the material’s practical advantages is its high optical absorption coefficient, which allows efficient light harvesting in films only a few hundred nanometers thick. This reduces material usage and supports the fabrication of lightweight and semi transparent devices. In addition, the absorber layer can be deposited at comparatively low temperatures, lowering energy consumption during manufacturing and improving compatibility with large area processing methods.
Progress in this material system had stalled for several years, with efficiencies remaining below ten percent despite incremental refinements. The UNSW researchers traced this limitation to an internal energy barrier formed during hydrothermal deposition. An uneven distribution of sulfur and selenium within the absorber created regions that impeded charge carrier transport, increasing recombination before the electrical current could be collected.
By introducing a controlled amount of sodium sulfide during synthesis, the team stabilized the reaction kinetics responsible for film formation. This adjustment led to a more uniform elemental distribution across the absorber layer, reducing transport losses and improving charge collection efficiency. Laboratory devices exceeded eleven percent efficiency, while independent certification confirmed a stabilized performance of 10.7 percent.
Although this efficiency remains below that of commercial silicon cells, the result is significant from a materials engineering perspective. It demonstrates that the long standing performance ceiling was not intrinsic to antimony chalcogenide itself but was instead linked to processing related electronic barriers. This insight provides a clearer pathway for further improvements through defect reduction and chemical passivation strategies.
Beyond tandem solar cells, antimony chalcogenide offers characteristics that support alternative applications. Its thin film nature and semi transparency make it suitable for integration into window systems, while its spectral response aligns well with indoor lighting conditions. These properties make it relevant for low power electronics such as sensors, electronic labels, and self powered devices where long term stability and consistent performance under low light are critical.
The research contributes to a broader effort within photovoltaic engineering to expand the range of viable materials that can complement silicon rather than replace it. As tandem architectures move closer to commercial deployment, materials that balance efficiency potential with stability and scalable manufacturing will play an increasingly important role. This latest result positions antimony chalcogenide as a credible option within that evolving landscape.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
