Researchers at the University of New South Wales (UNSW), Australia, have set a new record for the efficiency of kesterite (CZTS) solar cells, which could serve as a sustainable and cost-effective alternative or complement to silicon-based panels.
A team led by Scientia Professor Xiaojing Hao from the School of Photovoltaic and Renewable Energy Engineering achieved a 13.2% efficiency for high bandgap kesterite solar cells, enhanced with hydrogen.
Kesterite, a naturally occurring mineral, can also be synthesized using copper, zinc, tin, and sulfur, materials that are abundant and non-toxic.
CZTS is considered a promising material due to its environmental benefits and potential for long-term photovoltaic performance. However, its efficiency has been hindered by defects formed during production.
To address this, the UNSW team, including Dr Kaiwen Sun and Dr Jialiang Huang, introduced a hydrogen-based annealing process to mitigate these defects.
“In basic terms, to create CZTS you take copper, tin, zinc, and sulphur and ‘cook’ them all together at a certain temperature which turns it into a material you can use as a semiconductor,” says Hao.
“The tricky part is controlling the defects that are introduced during that process. What we have shown in this work is that introducing hydrogen can ensure those defects have less of an impact – which is known as passivation.”
CZTS is particularly suited for tandem solar cells, which layer multiple materials to enhance efficiency. Hao expects the material to reach 15% efficiency within a year and sees potential for commercialization by 2030.
Her team is also researching perovskite as another possible silicon partner. While highly efficient, perovskite has stability challenges.
“Overall, I think we should be looking into all different types of materials for the top layer of tandem cells,” Hao concludes.
[Images credit: UNSW Sydney]
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