Nano-confinement Driven Modulation of Molecular Dipole Orientation and its effect on Ferroelectricity and Work-function in Piezoelectric Polymer

The synergistic influence of stress confinement phenomena has recently sparked substantial interest in research on nanoscale piezoelectricity and ferroelectricity in polymers.^1,2 Here, we demonstrate how the nanoconfinement driven morphological modification of a model ferroelectric polymer, poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)^3.4 into nanoparticles (0D), nanofibers (1D), and thin films (2D) affects molecular dipole orientation on the piezoelectric and ferroelectric capabilities. The molecular dipoles in 1D and 2D nanostructures are perpendicular to the substrate, whereas they are parallel in 0D nanoparticles. This phenomenon significantly controls the nanoscale piezo- and ferro-electric features of the P(VDF-TrFE) in different morphologies. It is noteworthy that the molecule dipole orientation controls the surface functionality and work-function of the nanostructures. Work-functions in 0D and 1D nanostructures range from 5.24 eV and 4.87 eV to 4.72 eV in 2D, respectively. This wide range of work-function tunability was further utilized in effective frictional charge generation owing to the principle of triboelectricity for energy harvesting. This study renders a comprehensive understanding on effect of molecular dipole orientation on the material properties in dimensionally confined nanostructures of P(VDF-TrFE).

References:

1. Nano Energy 100 (2022) 107451.

2. Appl. Phys. Lett. 2021, 119, 252902.

3. Macromol. Rapid Commun. 2011, 32, 831-837.

4. Science 1983, 220, 1115-1121.