New Insight into Nanoscale Identification of the Polar Axis Direction in Organic Ferroelectric Films - Université de Lille
Article Dans Une Revue ACS Applied Materials & Interfaces Année : 2023

New Insight into Nanoscale Identification of the Polar Axis Direction in Organic Ferroelectric Films

Résumé

Ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-co-TrFE)] thin films have been deposited by spin-coating onto the Bi0.5Na0.5TiO3(BNT)/LNO/SiO2/Si heterostructure. The copolymer microstructure investigated by using grazing-incidence wide-angle X-ray diffraction (GIWAXD) and deduced from the (200)/(110) reflections demonstrates that the b-axis in the P(VDF-co-TrFE) orthorhombic unit cell is either in the plane or out of the plane, depending on the face-on or on the two types of edge-on (called I and II) lamellar structures locally identified by atomic force microscopy (AFM). For edge-on I lamellae regions, the electroactivity (dzzeff ∼ −50.3 pm/V) is found to be twice as high as that measured for both edge-on II or face-on crystalline domains, as probed by piezoresponse force microscopy (PFM). This result is directly correlated to the direction of the ferroelectric polarization vector in the P(VDF-co-TrFE) orthorhombic cell: larger nanoscale piezoactivity is related to the b-axis which lies along the normal to the substrate plane in the case of the edge-on I domains. Here, the ability to thoroughly gain access to the as-grown polar axis direction within the edge-on crystal lamellae of the ferroelectric organic layers is evidenced by combining the nanometric resolution of the PFM technique with a statistical approach based on its spectroscopic tool. By the gathering of information at the nanoscale, two orientations for the polar b-axis are identified in edge-on lamellar structures. These findings contribute to a better understanding of the structure–property relationships in P(VDF-co-TrFE) films, which is a key issue for the design of future advanced organic electronic devices.
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Dates et versions

hal-04278730 , version 1 (23-11-2023)

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Sajmohan Mohandas Moolayil, Antonio Da Costa, Jean-Francois Tahon, Vincent Bouad, Arthur Hamieh, et al.. New Insight into Nanoscale Identification of the Polar Axis Direction in Organic Ferroelectric Films. ACS Applied Materials & Interfaces, 2023, ACS Applied Materials & Interfaces, 15 (44), pp.51663-51674. ⟨10.1021/acsami.3c08579⟩. ⟨hal-04278730⟩
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