Simulations of ferroelectric polymer film polarization: The role of dipole interactions

Authors

Chun-gang Duan, University of Nebraska-LincolnFollow
Wai-Ning Mei, University of Nebraska at OmahaFollow
Wei-Guo Yin, Zhejiang University
Jianjun Liu, University of Nebraska-OmahaFollow
J. R. Hardy, University of Nebraska-OmahaFollow
Stephen Ducharme, University of Nebraska-LincolnFollow
Peter A. Dowben, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

6-21-2004

Comments

Published in Physical Review B 69, 235106 (2004) (6 pages)
URL: http://link.aps.org/abstract/PRB/v69/e235106
doi:10.1103/PhysRevB.69.235106 Copyright 2004 American Physical Society. Used by permission.

Abstract

We present a systematic study of the dipole alignment in the polyvinylidene fluoride (PVDF) films using first-principles total energy calculations. The ground state of a single layer film is a state with all the dipoles lying parallel to the film plane. This can also be explained by a dipole-dipole interaction model. The induced mirror charges on conducting substrates or substrates with a non-negligible dielectric response play an important role in aligning the polarization perpendicular to the film. From fitting the ab initio calculations, we obtain an effective monomer dipole moment of 4.7×10^–30 C m. This corresponds to a spontaneous polarization of 0.087 C/m², which agrees with other theoretical and experimental values. Simulation reveals a more complex behavior for molecular bilayer. We studied three molecular multilayer structures to compare the total energy and model calculations. Close examination of these results provides a better understanding of PVDF film growth and dipole orientation on different substrates.