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Urbanaviciute, Indre
Publications (2 of 2) Show all publications
Urbanaviciute, I., Meng, X., Biler, M., Wei, Y., Cornelissen, T. D., Bhattacharjee, S., . . . Kemerink, M. (2019). Negative piezoelectric effect in an organic supramolecular ferroelectric. Materials Horizons, 6, 1688-1698
Open this publication in new window or tab >>Negative piezoelectric effect in an organic supramolecular ferroelectric
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2019 (English)In: Materials Horizons, ISSN 2051-6347, E-ISSN 2051-6355, Vol. 6, p. 1688-1698Article in journal (Refereed) Published
Abstract [en]

The vast majority of ferroelectric materials demonstrate a positive piezoelectric effect. Theoretically, the negative piezoelectric coefficient d33 could be found in certain classes of ferroelectrics, yet in practice, the number of materials showing linear longitudinal contraction with increasing applied field (d33 < 0) is limited to few ferroelectric polymers. Here, we measure a pronounced negative piezoelectric effect in the family of organic ferroelectric small-molecular BTAs (trialkylbenzene-1,3,5-tricarboxamides), which can be tuned by mesogenic tail substitution and structural disorder. While the large- and small-signal strain in highly-ordered thin-film BTA capacitor devices are dominated by intrinsic contributions and originates from piezostriction, rising disorder introduces additional extrinsic factors that boost the large-signal d33 up to −20 pm V’1 in short-tailed molecules. Interestingly, homologues with longer mesogenic tails show a large-signal electromechanical response that is dominated by the quadratic Maxwell strain with significant mechanical softening upon polarization switching, whereas the small-signal strain remains piezostrictive. Molecular dynamics and DFT calculations both predict a positive d33 for defect-free BTA stacks. Hence, the measured negative macroscopic d33 is attributed to the presence of structural defects that enable the dimensional effect to dominate the piezoelectric response of BTA thin films.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Textile, Rubber and Polymeric Materials Condensed Matter Physics Theoretical Chemistry
Identifiers
urn:nbn:se:liu:diva-160355 (URN)10.1039/C9MH00094A (DOI)
Available from: 2019-09-19 Created: 2019-09-19 Last updated: 2019-09-19Bibliographically approved
Gorbunov, A. V., Haedler, A. T., Putzeys, T., Zha, R. H., Schmidt, H.-W., Kivala, M., . . . Kemerink, M. (2016). Switchable Charge Injection Barrier in an Organic Supramolecular Semiconductor. ACS Applied Materials and Interfaces, 8(24), 15535-15542
Open this publication in new window or tab >>Switchable Charge Injection Barrier in an Organic Supramolecular Semiconductor
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2016 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 24, p. 15535-15542Article in journal (Refereed) Published
Abstract [en]

We disclose a supramolecular material that combines semiconducting and dipolar functionalities. The material consists of a discotic semiconducting carbonyl-bridged triarylamine core, which is surrounded by three dipolar amide groups. In thin films, the material self-organizes in a hexagonal columnar fashion through Jr-stacking of the molecular core and hydrogen bonding between the amide groups. Alignment by an electrical field in a simple metal/semiconductor/metal geometry induces a polar order in the interface layers near the metal contacts that can be reversibly switched, while the bulk material remains nonpolarized. On suitably chosen electrodes, the presence of an interfacial polarization field leads to a modulation of the barrier for charge injection into the semiconductor. Consequently, a reversible switching is possible between a high-resistance, injection-limited off-state and a low-resistance, space-charge-limited on-state. The resulting memory diode shows switchable rectification with on/off ratios of up to two orders of magnitude. This demonstrated multifunctionality of a single material is a promising concept toward possible application in lowcost, large-area, nonvolatile organic memories.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2016
Keywords
organic semiconductors; current switching; memories; polarization; rectification; dipolar switching; injection barrier
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-130278 (URN)10.1021/acsami.6b02988 (DOI)000378584800072 ()27246280 (PubMedID)
Note

Funding Agencies|NWO Nano program; Bavarian State Ministry of Science, Research, and the Arts for the Collaborative Research Network Solar Technologies go Hybrid; Deutsche Forschungsgemeinschaft (DFG) [SFB 953]; Vetenskapsradet [2015-03813]

Available from: 2016-08-01 Created: 2016-07-28 Last updated: 2017-11-28
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