Researchers at the University of New South Wales (UNSW) have shattered the world record for the efficiency of kesterite solar cells, which is considered a promising alternative to traditional silicon-based solar panels.
The team has achieved “a best-ever efficiency of 13.2% for high bandgap kesterite solar cells, which had been enhanced with hydrogen.”
Kesterite is a naturally occurring mineral composed of copper, zinc, tin, and sulfur (CZTS). It has long been recognized for its potential in solar cell applications.
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It is abundant, non-toxic, and cost-effective to produce, making it an attractive candidate for next-generation solar technology.
“Silicon modules have almost reached the limit of their theoretical efficiency, so what we are trying to do is answer the question coming from the PV industry as to what the next generation of cells will be made of,” said Scientia Professor Xiaojing Hao, who led the research team.
Overcoming challenges in kesterite production
Previous attempts to harness kesterite’s full potential have been hampered by defects formed during the manufacturing process.
The team tackled this challenge by employing a novel approach involving hydrogen treatment during the fabrication process.
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This technique, known as passivation, effectively neutralizes the detrimental effects of defects and allows the kesterite solar cell to convert sunlight into electricity with significantly improved efficiency.
The breakthrough builds upon six years of research by the UNSW team, which initially achieved an 11.4% efficiency for CZTS cells. Now, with the introduction of hydrogen passivation, they have shattered the previous record and opened up new possibilities for kesterite solar technology.
“The big picture here is that we ultimately want to make electricity cheaper and greener to generate,” said Prof. Hao.
“CZTS is an ideal material for solar cells because it is environmentally friendly, cost-effective, and exhibits long-term stability.”
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The UNSW team’s achievement has significant implications for the future of solar energy.
Well-suited for tandem solar cells
Kesterite solar cells are well-suited for use in tandem solar cells, which combine different materials to capture a broader spectrum of sunlight and achieve higher efficiencies.
The team is optimistic that this breakthrough will pave the way for the commercialization of kesterite solar cells by 2030.
“There is still work to be done to find ways to further reduce the defects we find in CZTS, either during the fabrication or via post-fabrication treatments,” Prof. Hao acknowledged.
“But we know that this is a good material. When we consider the requirements from the bottom up, we know that we need something that is widely abundant, that is environmentally friendly, that has good optoelectronic properties and can last a long time – and CZTS fits the bill.”
Kesterite offers sustainable solution
The team aims to explore alternative materials for solar cells, including perovskite.
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While perovskite boasts higher efficiencies, it suffers from stability issues and toxicity concerns. In contrast, kesterite offers a more sustainable and environmentally friendly solution.
“When you go the other way, from the top to the bottom, maybe with something like perovskite, you can get really high performance and high efficiency at the beginning, but it’s much less stable and the panels might only last for one year so it’s not sustainable,” she concluded.
“It can take a long time to solve those problems, whereas with CZTS if we can get it to 20% efficiency then I think it will really take off because there are no other limitations since it meets all the criteria for the type of material we want to be using.”