| 1. |
- Choi, Hyeon-Seo, et al.
(författare)
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Oriented Crystal Growth during Perovskite Surface Reconstruction
- 2022
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 14:45, s. 51149-51156
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Tidskriftsartikel (refereegranskat)abstract
- Surface passivation has become a key strategy for an improvement in power conversion efficiency (PCE) of perovskite solar cells (PSCs) since PSCs experienced a steep increase in PCE and reached a comparably matured point. Recently, surface passivation using a mixed salt of fluorinated alkyl ammonium iodide and formamidinium bromide demon-strated a remarkable improvement in both performance and stability, which can be tuned by the length of the alkyl chain. Nevertheless, the role of the alkyl chain in manipulating surface-limited crystal growth was not fully understood, preventing a further progress in interface control. In this study, we found that the length of the fluorine-substituted alkyl chain governed the crystal formation dynamics by manipulating surface tensions of different crystal orientations. The overall enhancement of the (001) plane, being the most favored, commonly resulted from the surface reformation of the perovskite film regardless of the chain length, while the highly oriented (001) over (111) was monitored with a particular chain length. The enhanced crystal orientation during surface recrystallization was responsible for the low trap density and thus effectively suppressed charge recombination at the interface, resulting in a considerable increase in open-circuit voltage and fill factor.
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| 2. |
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| 3. |
- Choi, Yujin, et al.
(författare)
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National prevalence and trends in food labeling awareness, comprehension, usage, and COVID-19 pandemic-related factors in South Korea, 2014-2022
- 2024
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Ingår i: Scientific Reports. - : NATURE PORTFOLIO. - 2045-2322. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Although food labeling on food packages is crucial for promoting a healthy diet, limited research has been conducted on how the COVID-19 pandemic (hereinafter "the pandemic") has affected food labeling awareness. Therefore, this study aims to analyze the changes in trends in food labeling awareness, comprehension, and usage in South Korea during the pandemic. We utilized a nationwide, large-scale, and long-term dataset provided by the Korea Community Health Survey (KCHS) from 2014 to 2022 (total = 1,756,847 participants). This allowed the researchers to assess the long-term trends in the prevalence of food labeling awareness, comprehension, and usage. Furthermore, we investigated the factors associated with awareness specifically related to the pandemic. In total, 1,756,847 adults (54.19% women) participated in this study. The upward slope in overall food labeling awareness became less pronounced and even exhibited a downward slope during the pandemic (beta diff - 1.759; 95% CI - 1.874 to - 1.644). The upward slope in food labeling comprehension and usage became more pronounced during the pandemic (comprehension: beta diff 0.535; 95% CI 0.436-0.634; usage: beta diff 0.693; 95% CI 0.601-0.785). The vulnerability factors associated with lower food labeling awareness during the pandemic included older age, male, obesity, residing in rural areas, lower household income, lower educational level, smoking, and increased alcohol consumption. This study analyzed the 9-year trend in the prevalence of food labeling awareness, comprehension, and usage based on nationally representative data of adults in South Korea from 2014 to 2022. Our findings suggest that personalized nutrition strategies are needed to recognize vulnerable groups with risk factors and improve food labeling awareness among Korean adults during the pandemic.
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| 4. |
- Suo, Jiajia, et al.
(författare)
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Surface Reconstruction Engineering with Synergistic Effect of Mixed-Salt Passivation Treatment toward Efficient and Stable Perovskite Solar Cells
- 2021
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Ingår i: Advanced Functional Materials. - : John Wiley & Sons. - 1616-301X .- 1616-3028. ; 31:34
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Tidskriftsartikel (refereegranskat)abstract
- Surface passivation treatment is a widely used strategy to resolve trap-mediated nonradiative recombination toward high-efficiency metal-halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well as an in-depth understanding of its passivation mechanism. Here, a systematic study on a mixed-salt passivation strategy of formamidinium bromide (FABr) coupled with different F-substituted alkyl lengths of ammonium iodide is demonstrated. It is obtained better device performance with decreasing chain length of the F-substituted alkyl ammonium iodide in the presence of FABr. Moreover, they unraveled a synergistic passivation mechanism of the mixed-salt treatment through surface reconstruction engineering, where FABr dominates the reformation of the perovskite surface via reacting with the excess PbI2. Meanwhile, ammonium iodide passivates the perovskite grain boundaries both on the surface and top perovskite bulk through penetration. This synergistic passivation engineer results in a high-quality perovskite surface with fewer defects and suppressed ion migration, leading to a champion efficiency of 23.5% with mixed-salt treatment. In addition, the introduction of the moisture resisted F-substituted groups presents a more hydrophobic perovskite surface, thus enabling the decorated devices with excellent long-term stability under a high humid atmosphere as well as operational conditions.
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