Carl Henrik Gørbitz

• Litterst, Maximilian; Jannasch, Ramon; Balagopalan, Manjunath; Görbitz, Carl Henrik; Nilsen, Ola & Berland, Kristian [Show all 7 contributors for this article] (2026). Humidity-Tunable Organic Ferroelectric with Low Coercive Field. ACS Materials Letters. 8(7), p. 1982–1989. doi: 10.1021/acsmaterialslett.6c00243. Full text in Research Archive Show summary

  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.

• Litterst, Maximilian; Balagopalan, Manjunath; Jannasch, Ramon; Sødahl, Elin Dypvik; Seyedraoufi, Seyedmojtaba & Gørbitz, Carl Henrik [Show all 9 contributors for this article] (2026). Experimentally confirmed ferroelectricity in organic compounds identified by database mining. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 28, p. 4636–4647. doi: 10.1039/d5cp03009a. Full text in Research Archive Show summary

  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.

• Mandal, Arkalekha; Mohn, Chris Erik; Görbitz, Carl Henrik & Roy, Anurag (2026). Cocrystal Engineering of Organic Semiconductors for Photovoltaic Applications: Modeling Excited-State Properties of a Charge Transfer Cocrystal of a Dicarbazole Donor and a Fluoranil Acceptor. Journal of Physical Chemistry C. ISSN 1932-7447. 130(2), p. 897–897. doi: 10.1021/acs.jpcc.5c06828. Full text in Research Archive Show summary

  With the recent advancements in lightweight, flexible, and environmentally benign organic supramolecular aggregates for various optoelectronic applications, cocrystals of aromatic π-donors and π-acceptors have emerged as promising n-type semiconductors and near-infrared absorbers for enhanced photovoltaic properties. Herein, we demonstrate the electron-dominant charge transport and wide absorption spanning from ultraviolet (UV) to NIR-I region (375–800 nm) of a cocrystal with π-donor 4,4′-bis(carbazol-9-yl)biphenyl (CBP) and π-acceptor 1,4-tetrafluoro-p-benzoquinone (fluoranil) as the components. The crystal packing in CBP:(fluoranil)2 is characterized by mixed stacks of alternative CBP and fluoranil molecules tethered by strong face-to-face π···π stacking interactions. The electron-dominant charge transport in the CBP:(fluoranil)2 cocrystal is governed by the “superexchange” hopping mechanism along the D–A mixed π-stack and is dominated by factors like the energy and symmetry of the frontier molecular orbitals of the CBP and fluoranil moieties. The narrow bandgap (≈1.2 eV) and the high value of the superexchange electron transfer integral (≈100 meV) confirm the potential application of this cocrystal as the active layer material in n-type organic field effect transistors (OFETs). In addition, the strong absorption spanning from the UV to near-infrared region, narrow and direct bandgap, and low exciton binding energy indicate that the CBP:(fluoranil)2 cocrystal can also be exploited for photovoltaic applications. The electron–hole distribution offset, exciton size, and one-electron transition density matrix analyses confirm facile charge transfer exciton generation and dissociation leading to free charge carriers. The calculated value of spectroscopy-limited maximum efficiency (SLME) from periodic density functional theory (DFT) calculations for this cocrystal shows that it can reach a photoconversion efficiency (PCE) of 31%, implying its potential applicability as a practical photovoltaic material.

• Mandal, Arkalekha; Mohn, Chris Erik; Görbitz, Carl Henrik; Rogowska, Melania & Nilsen, Ola (2025). Elucidating the role of charge transfer on semiconductor properties in a new donor–acceptor cocrystal 1,5-dihydroxynaphthalene : TCNQ. Molecular Systems Design & Engineering. 10(7), p. 519–533. doi: 10.1039/d5me00033e. Full text in Research Archive Show summary

  In this work, we have investigated the semiconducting properties of an unprecedented 1 : 1 π-stacked donor–acceptor cocrystal of 1,5-dihydroxynaphthalene (DHN) as the π-donor (D) with 7,7′,8,8′-tetracyanoquinodimethane (TCNQ) as the π-acceptor (A). Molecular semiconductors with electron dominant transport, narrow bandgap, solution processing ability, air-stability are highly sought-after for application in n-channel organic field effect transistors. The DHN : TCNQ cocrystal shows n-type semiconductor nature with a narrow bandgap of around 1 eV, and a low LUMO energy level (−3.8 eV) making it less prone to areal degradation. The electron dominant transport in this cocrystal is described by assuming that electron and hole hop via a super-exchange mechanism along the mixed ⋯D–A⋯ π-stack direction. The participation of bridging molecular orbitals other than donor HOMO make a significant contribution to the super-exchange electron transfer, thus resulting in electron hopping from acceptor to acceptor which is four times larger than the value of hole hopping from donor to donor. Detailed analysis of crystal packing and electronic properties demonstrate that the super-exchange charge carrier transport is facilitated by strong π⋯π stacking interaction between the donor and acceptor, and prominent charge transfer.

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• Jemterud, Torkild; Bjorå, Charlotte Sletten; Görbitz, Carl Henrik; Bøhn, Einar Duenger; Dietrichs, Erik Sveberg & Paus-Knudsen, Julie Sørlie [Show all 8 contributors for this article] (2025). Abels tårns ekstrasending. [Radio]. P2. doi: https:/radio.nrk.no/podkast/abels_taarn/sesong/2025. Full text in Research Archive
• Berland, Kristian; Sødahl, Elin Dypvik; Seyedraoufi, Seyedmojtaba; Nilsen, Ola; Görbitz, Carl Henrik & Walker, Julian Bradley [Show all 7 contributors for this article] (2025). Ferroelectric and piezoelectric molecular crystals: From database mining to computational design. Full text in Research Archive
• Bjorå, Charlotte Sletten; Görbitz, Carl Henrik & Bratlie, Sigrid (2024). Abels tårn. [Radio]. NRK. Full text in Research Archive
• Sødahl, Elin Dypvik; Seyedraoufi, Seyedmojtaba; Balagopan, Manjunath; Walker, Julian Bradley; Gørbitz, Carl Henrik & Helland-Madsen, Georg [Show all 8 contributors for this article] (2024). Computational modeling of ferroelectric and piezoelectric plastic crystals​. Full text in Research Archive
• Sødahl, Elin Dypvik; Seyedraoufi, Seyedmojtaba; Gørbitz, Carl Henrik & Berland, Kristian (2024). Screening the CSD to identify ferroelectric plastic crystals. Full text in Research Archive
• Berland, Kristian; Gørbitz, Carl Henrik & Sødahl, Elin Dypvik (2024). Molecular ferroelectric plastic crystals : computational modeling and discovery. Norges miljø- og biovitenskapelige universitet (NMBU). Full text in Research Archive Show summary

  In recent years, ferroelectric molecular crystals, specifically those with globular molecules, have gained interest due to their rapid ferroelectric switching, high Curie temperatures, and multiaxial ferroelectricity. These materials can host mesophases characterized by an orientational disorder of their molecular species. Close-packed mesophase materials can be malleable and ductile, and are thus called plastic crystals. Their unique mechanical properties are enabled by numerous slip planes and broken intermolecular bonds due to molecular rotation. This thesis focuses on the computational discovery and modeling of mesophase molecular ferroelectrics. While there is some insight into the ferroelectric mechanisms in plastic crystals, their piezoelectric mechanisms are less explored. Density functional theory (DFT) computations for a selection of known ferroelectrics found that materials composed of globular species showed sizable shear piezoelectric responses due to molecular rotations under strain. Systems with higher hydrogen-bond density show smaller responses, as these bonds can hinder rotation. The plastic crystals displayed small dielectric responses and large compliance, resulting in a large electromechanical coupling factor and thus potential for energy harvesting application. A combined experimental and theoretical study of tetraethylammonium bromotrichloroferrite found that the material exhibits a small and stable piezoelectric response, which together with the small elastic moduli makes the material inhabiting a unique parameter space. Despite the growing interest, there are still fairly few reported ferroelectric molecular crystals. This motivated a screening study of the Cambridge Structural Database to identify ferroelectrics likely to display a disordered mesophase. Crystal structures, molecular geometry, and hydrogen-bond patterns were investigated to find materials that allow for molecular reorientation. Out of the 75 materials identified, 54 had not been studied for ferroelectric and related properties earlier. Furthermore, 20 of these were found likely to exhibit a plastic mesophase. DFT computations predicted spontaneous polarization above 10 µC/cm 2 for 17 materials with room-temperature ferroelectric phases, making them promising for technological applications. To gain an understanding of the dynamical disorder in molecular ferroelectrics, we employed a machine-learned force field (MLFF) to study the temperature-dependent behavior of HdaboClO4 . The molecular dynamics (MD) simulations provided a prediction of the thermal expansion and molecular reorientation in line with experimental measurements. MLFFs can give insight into chemical reactions, as they do not demand pre-defined bonding patterns. This enabled the study of proton transfer, revealing both an increasing transfer frequency at elevated temperatures and the change in orientation of hydrogen-bonded chains of Hdabco + molecules. The combination of DFT and MD with MLFFs makes a well-equipped toolbox to investigate the ferroelectric, piezoelectric, and dynamical properties of this promising group of materials. Combining these approaches with database screening can accelerate the development of materials for technological applications.

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