A van der Waals density functional theory study of poly(vinylidene difluoride) crystalline phases

F. Pelizza, B. Smith, K. Johnston

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Ferroelectric polymers, such as poly(vinylidene difluoride) (PVDF), have many potential applications in flexible electronic devices. PVDF has six experimentally observed polymorphs, three of which are ferroelectric. In this work we use density functional theory to investigate the structural properties, energetics and polarisation of the stable α-phase, its ferroelectric analogue, the δ-phase, and the β-phase, which has the best ferroelectric properties. The results from a variety of exchange and correlation functionals were compared and it was found that van der Waals (vdW) interactions have an important effect on the calculated crystal structures and energetics, with the vdW-DF functional giving the best agreement with experimental lattice parameters. The spontaneous polarisation was found to strongly correlate with the unit cell volumes, which depend on the functional used. While the relative phase energies were not strongly dependent on the functional, the cohesive energies were significantly underestimated using the PBE functional. The inclusion of vdW interactions is, therefore, important to obtain the correct lattice structures, polarisation and energetics of PVDF polymorphs.
LanguageEnglish
Pages1733-1742
Number of pages10
JournalEuropean Physical Journal - Special Topics
Volume225
Issue number8
Early online date18 Jul 2016
DOIs
Publication statusPublished - 31 Oct 2016

Fingerprint

difluorides
vinylidene
Ferroelectric materials
Density functional theory
density functional theory
Crystalline materials
polarization
Polarization
Polymorphism
deuterium fluorides
Flexible electronics
functionals
lattice parameters
interactions
inclusions
analogs
Lattice constants
Structural properties
Polymers
crystal structure

Keywords

  • ferroelectric polymers
  • poly(vinylidene difluoride)
  • PVDF
  • flexible electronic devices
  • crystal structures

Cite this

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title = "A van der Waals density functional theory study of poly(vinylidene difluoride) crystalline phases",
abstract = "Ferroelectric polymers, such as poly(vinylidene difluoride) (PVDF), have many potential applications in flexible electronic devices. PVDF has six experimentally observed polymorphs, three of which are ferroelectric. In this work we use density functional theory to investigate the structural properties, energetics and polarisation of the stable α-phase, its ferroelectric analogue, the δ-phase, and the β-phase, which has the best ferroelectric properties. The results from a variety of exchange and correlation functionals were compared and it was found that van der Waals (vdW) interactions have an important effect on the calculated crystal structures and energetics, with the vdW-DF functional giving the best agreement with experimental lattice parameters. The spontaneous polarisation was found to strongly correlate with the unit cell volumes, which depend on the functional used. While the relative phase energies were not strongly dependent on the functional, the cohesive energies were significantly underestimated using the PBE functional. The inclusion of vdW interactions is, therefore, important to obtain the correct lattice structures, polarisation and energetics of PVDF polymorphs.",
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A van der Waals density functional theory study of poly(vinylidene difluoride) crystalline phases. / Pelizza, F.; Smith, B.; Johnston, K.

In: European Physical Journal - Special Topics, Vol. 225, No. 8, 31.10.2016, p. 1733-1742.

Research output: Contribution to journalArticle

TY - JOUR

T1 - A van der Waals density functional theory study of poly(vinylidene difluoride) crystalline phases

AU - Pelizza, F.

AU - Smith, B.

AU - Johnston, K.

PY - 2016/10/31

Y1 - 2016/10/31

N2 - Ferroelectric polymers, such as poly(vinylidene difluoride) (PVDF), have many potential applications in flexible electronic devices. PVDF has six experimentally observed polymorphs, three of which are ferroelectric. In this work we use density functional theory to investigate the structural properties, energetics and polarisation of the stable α-phase, its ferroelectric analogue, the δ-phase, and the β-phase, which has the best ferroelectric properties. The results from a variety of exchange and correlation functionals were compared and it was found that van der Waals (vdW) interactions have an important effect on the calculated crystal structures and energetics, with the vdW-DF functional giving the best agreement with experimental lattice parameters. The spontaneous polarisation was found to strongly correlate with the unit cell volumes, which depend on the functional used. While the relative phase energies were not strongly dependent on the functional, the cohesive energies were significantly underestimated using the PBE functional. The inclusion of vdW interactions is, therefore, important to obtain the correct lattice structures, polarisation and energetics of PVDF polymorphs.

AB - Ferroelectric polymers, such as poly(vinylidene difluoride) (PVDF), have many potential applications in flexible electronic devices. PVDF has six experimentally observed polymorphs, three of which are ferroelectric. In this work we use density functional theory to investigate the structural properties, energetics and polarisation of the stable α-phase, its ferroelectric analogue, the δ-phase, and the β-phase, which has the best ferroelectric properties. The results from a variety of exchange and correlation functionals were compared and it was found that van der Waals (vdW) interactions have an important effect on the calculated crystal structures and energetics, with the vdW-DF functional giving the best agreement with experimental lattice parameters. The spontaneous polarisation was found to strongly correlate with the unit cell volumes, which depend on the functional used. While the relative phase energies were not strongly dependent on the functional, the cohesive energies were significantly underestimated using the PBE functional. The inclusion of vdW interactions is, therefore, important to obtain the correct lattice structures, polarisation and energetics of PVDF polymorphs.

KW - ferroelectric polymers

KW - poly(vinylidene difluoride)

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KW - flexible electronic devices

KW - crystal structures

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