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Large Converse Piezoelectric Effect Measured on a Single Molecule on a Metallic Surface.

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Bibliographic Details
Title:	Large Converse Piezoelectric Effect Measured on a Single Molecule on a Metallic Surface.
Authors:	Stetsovych, Oleksandr¹, Mutombo, Pingo¹, Švec, Martin^1,2, Šámal, Michal³, Nejedlý, Jindřich³, Císařová, Ivana⁴, Vázquez, Héctor¹, Moro-Lagares, María^1,2, Berger, Jan¹, Vacek, Jaroslav³, Stará, Irena G.³, Starý, Ivo³ stary@uochb.cas.cz, Jelínek, Pavel^1,2 pavel.jelinek@fzu.cz
Source:	Journal of the American Chemical Society. 1/24/2018, Vol. 140 Issue 3, p940-946. 7p.
Subjects:	Piezoelectricity, Electric properties of materials, Metallic surfaces, Single molecule research, Single molecules spectra, Molecular spectra, Atomic force microscopy, Density functional theory
Abstract:	The converse piezoelectric effect is a phenomenon in which mechanical strain is generated in a material due to an applied electrical field. In this work, we demonstrate the converse piezoelectric effect in single heptahelicene-derived molecules on the Ag(111) surface using atomic force microscopy (AFM) and total energy density functional theory (DFT) calculations. The force-distance spectroscopy acquired over a wide range of bias voltages reveals a linear shift of the tip-sample distance at which the contact between the molecule and tip apex is established. We demonstrate that this effect is caused by the bias-induced deformation of the spring-like scaffold of the helical polyaromatic molecules. We attribute this effect to coupling of a soft vibrational mode of the molecular helix with a vertical electric dipole induced by molecule-substrate charge transfer. In addition, we also performed the same spectroscopic measurements on a more rigid o-carborane dithiol molecule on the Ag(111) surface. In this case, we identify a weaker linear electromechanical response, which underpins the importance of the helical scaffold on the observed piezoelectric response. [ABSTRACT FROM AUTHOR]
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Database:	Engineering Source

Description
Abstract:	The converse piezoelectric effect is a phenomenon in which mechanical strain is generated in a material due to an applied electrical field. In this work, we demonstrate the converse piezoelectric effect in single heptahelicene-derived molecules on the Ag(111) surface using atomic force microscopy (AFM) and total energy density functional theory (DFT) calculations. The force-distance spectroscopy acquired over a wide range of bias voltages reveals a linear shift of the tip-sample distance at which the contact between the molecule and tip apex is established. We demonstrate that this effect is caused by the bias-induced deformation of the spring-like scaffold of the helical polyaromatic molecules. We attribute this effect to coupling of a soft vibrational mode of the molecular helix with a vertical electric dipole induced by molecule-substrate charge transfer. In addition, we also performed the same spectroscopic measurements on a more rigid o-carborane dithiol molecule on the Ag(111) surface. In this case, we identify a weaker linear electromechanical response, which underpins the importance of the helical scaffold on the observed piezoelectric response. [ABSTRACT FROM AUTHOR]
ISSN:	00027863
DOI:	10.1021/jacs.7b08729