Dipole switching dynamics in P(VDF-TrFE) film revealed by in-situ polarization switching and infrared spectroscopy measurements with high-time resolution

Abstract

Although P(VDF-TrFE) is an important ferroelectric material, its polarization switching details, especially at the nucleation site of the polarized domain, are unknown. Herein, a setup combining a ferroelectricity evaluation system and a Fourier-transform infrared spectrometer with a 70 ms time resolution was developed to simultaneously monitor polarization-switching current and absorption changes associated with the molecular chain rotation of P(VDF-TrFE) under an electric field. Time variations of absorbance associated with CF 2 symmetric vibration in response to the applied electric field served as an indicator of dipole rotation. The onsets and peaks of the polarization-switching current, which appeared before the dynamic molecular orientation, changed across the material. The complementary characterization revealed that the P(VDF-TrFE) polarized domain first nucleates at the interface and grows toward the inner side of film to achieve a completely polarized state of the film. • Molecular rotation of P(VDF-TrFE) associated with its polarization reversal was monitored by IR. • Drastic absorbance changes occur beyond coercive electric field of P(VDF-TrFE). • Polarized domain first nucleates at interface, then grows toward film interior. • As a result, a completely polarized state of film is achieved.