Publikasjoner
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Litterst, Maximilian; Jannasch, Ramon; Balagopalan, Manjunath; Görbitz, Carl Henrik; Nilsen, Ola & Berland, Kristian
[Vis alle 7 forfattere av denne artikkelen]
(2026).
Humidity-Tunable Organic Ferroelectric with Low Coercive Field.
ACS Materials Letters.
8(7),
s. 1982–1989.
doi:
10.1021/acsmaterialslett.6c00243.
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As compared to their inorganic counterparts, organic ferroelectrics offer vast design freedom, enabling the creation of materials with unprecedented properties. Here, we present temperature- and humidity-dependent ferroelectric switching measurements on thin polycrystalline films of an organic ionic cocrystal that was identified by database mining as potentially ferroelectric. The experiments reveal exceptionally low coercive fields, down to ∼0.2 V/μm, depending on conditions, while maintaining reasonable remnant polarizations around 15 μC/cm2. We observe a pronounced dependence of the ferroelectric properties on switching frequency, temperature and, strikingly, ambient humidity. Interestingly, the ferroelectric behavior appears to be coupled to the complex electrical conductivity. We interpret our findings in terms of a multi-step polarization reversal mechanism, involving a combination of proton transfer and molecular rotations, where the former is thought to also be responsible for the observed long-range charge transport. These properties may find applications in new classes of tunable or environment-responsive ‘smart’ materials.
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Litterst, Maximilian; Balagopalan, Manjunath; Jannasch, Ramon; Sødahl, Elin Dypvik; Seyedraoufi, Seyedmojtaba & Gørbitz, Carl Henrik
[Vis alle 9 forfattere av denne artikkelen]
(2026).
Experimentally confirmed ferroelectricity in organic compounds identified by database mining.
Physical Chemistry, Chemical Physics - PCCP.
ISSN 1463-9076.
28,
s. 4636–4647.
doi:
10.1039/d5cp03009a.
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Compared to inorganic ferroelectrics, the breadth of polarization switching mechanisms in organic ferroelectrics is very broad and far from fully characterized or understood. Here, we experimentally investigate the absence or presence of ferroelectric properties in a selection of organic materials that have been identified by a data mining approach using heuristic measures to identify stretchability, aiming to assess the practical potential of this approach. From a set of 66 candidate materials, 4 were selected for detailed analysis. These were investigated structurally using powder X-ray diffraction and electrically, using capacitance–voltage spectroscopy and polarization hysteresis measurements. Despite large differences in stability and background conductivity, all compounds exhibited ferroelectric behavior at room temperature, with relatively large polarization values. Specifically, the ferroelectric properties of one material show a strong dependency on the ambient humidity, whereas another showed a strong coupling between background conductivity and ferroelectric switching. These effects are not yet fully understood and lie beyond the scope of this study. Of the remaining two compounds, one was found to be unstable at room temperature whereas the other displayed multiple polymorphs, complicating reproducibility and limiting their practical potential. Overall, these results confirm the relevance of the data mining prediction scheme and suggest that a significant fraction of the identified but so far untested materials may also be ferroelectric.
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Publisert
30. mars 2023 16:02
- Sist endret
19. apr. 2023 12:22