Researchers in South Korea improved the performance of tin monosulfide (SnS) solar cells with a potassium fluoride-assisted post-treatment and vapor transport deposition process. The treated solar cells had an energy conversion efficiency of 4.10% and reduced recombination sites, compared to 3.42% for untreated devices.
Research led by Chonnam National University in South Korea has improved the performance of tin monosulfide (SnS) solar cells with a potassium fluoride-assisted (KF) post-treatment and a vapor transport deposition (VTD) process. The treated solar cells had an energy conversion efficiency of 4.10% and reduced recombination sites, compared to control devices.
The research topic is complementary to the research group’s previous research on germanium oxide (GeOx), which achieved a cell efficiency of 4.81%, said the study’s first author, Rahul Kumar Yadav.
“The KF treatment improves the intrinsic quality of the SnS absorber surface and provides a superior basis for subsequent interface engineering, while the GeOX interlayer optimizes band alignment and suppresses recombination at rear contact,” shared Kumar Yadav pv magazine.
“In our ongoing work we actively combine KF surface treatment with GeOX back interface engineering, as we expect their integration to deliver further gains in terms of voltage, operational stability and overall device efficiency,” he added.
In the study, the researchers varied the concentration of the KF solution to measure the effect of drop-cast KF surface treatment on the structural, morphological and photovoltaic properties of VTD-SnS absorber layers.
Testing showed that the KF treatment improved “film uniformity, densification and wettability.” Devices based on the optimized KF-treated SnS absorber had a PCE of 4.10%, an improvement compared to 3.42% for untreated devices, with further analysis revealing reduced recombination sites.
“The post-treatment of the KF-assisted solution functions as a surface modulation step, improving grain connectivity, reducing surface roughness and passivating electrically active defects,” says Kumar Yadav, adding that the resulting higher open-circuit voltage and fill factor enabled improved efficiency “without changing the overall device architecture.”
The researchers concluded that the study represents a “scalable strategy to overcome important interfacial limitations” and advance SnS thin-film solar photovoltaics.
Korea Aerospace University and Kyungpook National University also participated in the study.
The work is described in detail in “By modulating the surface morphology via post-treatment with potassium fluoride solutions, VTD-SnS thin-film solar cells can achieve an efficiency of more than 4%”, which appears in Materials today energy.
Looking ahead, the group is focused on developing SnS thin-film solar cells above the 4% efficiency threshold “through coordinated absorber surface, heterojunction interface and back-interface engineering, while maintaining compatibility with scalable manufacturing processes,” said Kumar Yadav.
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