Probing Confinement Effects on Multilayered Ferroelectric Polymer Films Using Second Harmonic Generation
- PDF / 615,028 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 19 Downloads / 159 Views
Probing Confinement Effects on Multilayered Ferroelectric Polymer Films Using Second Harmonic Generation J. Jones1,2, L. Zhu3, N. Tolk1, and R. Mu1,2 1 Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37240, USA 2 Department of Physical and Life Sciences, Fisk University, Nashville, Tennessee 37208, USA 3 Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA ABSTRACT Electrical energy storage plays a key role in mobile electronic devices, stationary power systems, and hybrid electrical vehicles. High energy density capacitors based on dielectric polymers are a focus of increasing research effort motivated by the possibility to realize compact and flexible energy storage devices, taking advantage of light weight and facile processability of organic materials. In addition, dielectric polymers enjoy inherent advantages of self-healing mechanism and high breakdown strength, leading to capacitors with great reliability and high energy density. It is the focus of this group to develop a multilayered ferroelectric PVDF system for improved energy storage efficiency. These systems are fabricated using enabling technology in co-extrusion which allows more cost effective and large area device production as opposed to more conventional layer-by-layer techniques. Many efforts have been made by the team to fabricate these micro- and nano-layered systems resulting in much improved device performance. A three-time improvement of capacitive electrical energy density has been demonstrated. The focus of this research is to understand the physics of why these multilayered systems perform better than a single layer by developing a characterization technique using both confocal second harmonic generation (SHG) and electric field induced second harmonic (EFISH) laser spectroscopy. Our results have shown that SHG is a very sensitive, nondestructive and versatile technique that can be used to study the ferroelectric and structural properties of layered systems. When combined with EFISH this technique allows the interrogation of structural and dielectric properties within the individual layers and at the interfaces between the layers. Further, the proposed techniques can be readily employed in-situ which can provide information in real time during sample processing with static and timeresolved spectroscopic measurements. INTRODUCTION Considerable research has been done in the area of multilayer film capacitors and it has been demonstrated that dielectric breakdown strength can be dramatically enhanced by multilayering high dielectric constant polymers with a high breakdown strength [1]. Although it is speculated that the horizontal configuration of interfaces between two polymers plays an important role in enhancing the breakdown strength via a treeing phenomenon, no clear fundamental understanding has been provided/demonstrated thus far. It is of great interest to examine and evaluate how important the interfacial polarization at the interfaces betwe
Data Loading...
