With support from ACAP, UNSW researchers have highlighted that understanding and identifying the different atomic arrangements (polymorphs) of Copper Zinc Tin Sulfide (CZTS) is key to enhancing the efficiency of CZTS-based solar cells and advancing their commercialisation.
Their work, published in Solar RRL in February 2024, provides a foundation for improving CZTS solar cells, potentially pushing efficiency limits from the current 11.4% to over 15%.
Laying the groundwork for improving CZTS efficiency
Researchers Alireza Yaghoubi and Professor Xiaojing Hao have laid the groundwork for improving CZTS, a non-toxic, abundant material that absorbs sunlight in wavelengths not effectively captured by traditional silicon cells.
CZTS could boost silicon-based cells' efficiency when stacked in tandem systems without significant added cost. However, CZTS contains many defects, notably polymorphs (different atomic arrangements of the same compound), which limit efficiency by dissipating electrons.
The study focuses on understanding these polymorphs and suggests Raman spectroscopy as a method for their detection. Using computational methods, the team predicted the formation of various polymorphs and their effects on optoelectronic properties, aiming to systematically eliminate them.
Importance for solar technology development
As silicon solar cells near their theoretical efficiency limit, tandem cells involving new materials like CZTS could deliver the cheaper, more efficient and more sustainable solar technologies sought by ACAP and ARENA. While alternatives like halide perovskites are promising, they contain toxic lead and are unstable. If CZTS efficiency improves toward 15%, it could be a more stable and commercially viable option.
Next Steps
Future efforts to improve CZTS solar cell efficiency will focus on controlling the formation of these polymorphs to avoid undesirable defects and improve overall performance.
Their work featured on the May 2024 back cover of Solar RRL and was first published in February 2024.
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