Researchers from the University of New South Wales (UNSW) have achieved a breakthrough in solar cell technology, advancing the development of a new type of solar cell that could make future solar panels cheaper and more efficient.
The research team has set a new performance benchmark for solar cells made from antimony chalcogenide, reaching a certified efficiency of 10.7 per cent — the highest independently verified performance for this material anywhere in the world to date.
Antimony chalcogenide solar cells have emerged as a strong candidate for next-generation solar technology, given that such cells are made from abundant elements that are cheap to produce, and they are more stable than some newer solar materials that can degrade over time.
Antimony chalcogenide also has a high light absorption coefficient, which means only a layer 300 nanometres thick is enough to harvest sunlight efficiently.
Despite these advantages, progress in improving the efficiency of antimony chalcogenide has stalled at 10 per cent since 2020.
Researchers say the main obstacle was in the way the material formed during manufacturing, with two key elements, sulphur and selenium, not being evenly distributed in production.
Dr Chen Qian, the first author of the research paper and a post-doctoral fellow at the Photovoltaic and Renewable Energy Engineering at UNSW, said this uneven distribution created an “energy barrier” within the solar cell, blocking the flow of electrical charge generated by sunlight.
“It was like driving a car up a steep slope. If you do that, you need to use more fuel to get to the end, whereas if the road is flat, it’s more efficient to reach there,” Qian said.
“When the distribution of the elements inside the cell is more even, then the charge can move more easily through the absorber rather than being trapped before they are collected, which means more sunlight is converted into electricity.”
The solution to the problem was the addition of a small amount of sodium sulphide during the manufacturing process to stabilise the chemical reactions involved in forming the absorber layer.
The improved antimony chalcogenide solar cells reached a power conversion efficiency of 11.02 per cent in the UNSW laboratory, with a certified value of 10.7 per cent independently verified by the Commonwealth Scientific and Industrial Research Organisation (CSIRO).
“In the next few years, we will continue to work on reducing the defects in this material via that passivation process.
“We believe an achievable aim is to increase the efficiency up to 12 per cent in the near future by addressing the challenges that still remain, one step at a time,” said Dr Qian.