High Dielectric Constant Polymer Research Articles

Reducing dielectric loss by nanoconfined impurity ion transport in multilayer films under low electric fields

Despite higher dielectric constants than nonpolar polymers, polar polymers exhibit a high dielectric loss, which is detrimental for electric energy storage applications. To mitigate the ionic conduction loss, we have fabricated multilayer films (MLFs) with alternating layers of a high dielectric constant polar polymer and a high breakdown/low loss nonpolar polymer. In this study, we fabricated high temperature polycarbonate (HTPC)/poly (vinylidene fluoride) (PVDF) MLFs. The ionic transport behavior confined in the PVDF nanolayers under a low electric field was investigated using broadband dielectric spectroscopy (BDS). Direct analytical simulation was implemented to determine the concentration (n0) and diffusion coefficient (D0) for the confined impurity ions in PVDF at different temperatures and with and without the presence of lamellar crystals. It was found that both n0 and D0 increased upon increasing temperature. Using the simulated n0 and D0, nanoconfined transport of impurity ions was found for the PVDF layers with decreasing the layer thickness. Namely, a crossover PVDF layer thickness was predicted, below which the conduction loss from impurity ions substantially decreased. However, experimental BDS results systematically deviated from the theoretical predictions. One important reason for this deviation was attributed to the presence of edge-on lamellar crystals confined in the PVDF layers, which increased the tortuosity of the ion transport pathway. The knowledge gained in this study can be useful to understand the nanoconfinement and crystallinity effects on the ionic transport in MLFs, which is beneficial for the future development of MLFs for capacitor applications.

Enhanced breakdown strength and energy storage density in polyurea all-organic composite films

Polymer dielectric materials are highly desirable in electronic devices. However, neither low nor high dielectric constant polymers could meet the requirement of high energy storage application due to the contradiction between dielectric constant and breakdown strength. Herein, in order to obtain high performance polymer dielectrics, poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) is filled, as a functional material, into polyurea (PUA) matrix to form all-organic composites. Fortunately, PUA/P(VDF-TrFE-CFE) composites exhibit excellent performance with high dielectric constant and maintain high breakdown strength, resulting in enhanced energy storage density. The breakdown strength of composite film increases to 5130 kV cm−1, and the energy storage density can reach 4.3 J cm−3, which is much higher than pure PUA (2.4 J cm−3) and commercially biaxially oriented polypropylene (BOPP, 1.2 J cm−3). The enhancement of energy density of composite films is mainly attributed to the dipole interaction between PUA and P(VDF-TrFE-CFE) chains, which leads to increases of dielectric constant and maintain high breakdown strength simultaneously. This work provides an effective route to improve the energy density of linear dielectrics and showing great application potential for energy storage.

Amorphous Indium-Gallium-Zinc-Oxide Transistor Used Ion Gel Dielectric for Low Driving Voltage and Easy Processing

Transistors using organic materials are attracting huge attention in the market today due to their low cost and possibility of solution process. Moreover, since the organic materials used in transistors are intrinsically flexible, they are believed to be essential elements for the realization of flexible devices such as stretchable displays, rollable displays, and wearable devices. In most cases, however, because of the low dielectric constant of organic materials, the operating voltage of the transistor is very high when the organic materials are used as the gate dielectric layer. When the operating voltage of the transistor is high, two serious problems can occur. First, the high operating voltage can cause increased power consumption of the transistor. It is a fatal drawback that reduces the applicability to wireless device applications because in the case of wireless electronic equipment, lifetime of battery is limited. Also, as the operating voltage increases, additional gate driver integrated circuits are required to control the driving voltage. This leads to the increased process complexity, and reduces the price competitiveness of the device. Therefore, it can be said that the possibility of mass production and functionality of transistors using organic materials will increase by solving these two problems. As a result, various studies have been focused on solving these problems by reducing the thickness of dielectric or choosing unique organic material with high dielectric constant [2] [3]. In order to solve above problems, we proposed the transistors based on ion gel dielectric, which has high capacitance. Ion gel refers to the substance in which ionic liquid is trapped in the polymer matrix [1]. When the voltage is applied to the electrode, the ion gel forms an electric double layer (EDL) at the interface with the electrode. Since EDL forms a capacitor with thickness of several nanometers, the ion gel has a very high capacitance above 1μF/cm2 [1]. From the capacitance-frequency curve measurement of Metal-Ion gel insulator-Metal capacitor (MIM), it was confirmed that the capacitance of ion gel increased as the amount of ionic liquid in ion gel increased. In addition, MIM showed the capacitance around 1μF/cm2 even if the ionic liquid content was very small. In the case of the transistor structure, the transistor was easy to fabricate because the gate electrode was deposited on the same substrate as the source-drain electrode. The active layer had the width of 20μm and the length of 160μm. The gate leakage current of the transistor increased with increasing the amount of ionic liquid in the ion gel. By optimizing the amount of ionic liquid to control gate leakage current, the ionic liquid was chosen 3% relative to the polymer in terms of mass and the gate leakage current was reduced to several tens of picoampere. The transfer characteristic represented that turn-on-voltage was near -1V and on-off ratio was 3.93·104 when the gate voltage was swept from -4V to 4V. This result shows that the transistor can operate with well-behaved electrical property even at small driving voltage near 4V. The transistor made by simple fabrication with ion gel dielectric showed outstanding electrical characteristics with low driving voltage around 4V and this result will pave the way for the next generation of flexible devices. [1] Wang, H., Wang, Z., Yang, J., Xu, C., Zhang, Q., & Peng, Z. (2018). Ionic Gels and Their Applications in Stretchable Electronics. Macromolecular rapid communications, 39(16), 1800246. [2] Yoon, M. H., Yan, H., Facchetti, A., & Marks, T. J. (2005). Low-voltage organic field-effect transistors and inverters enabled by ultrathin cross-linked polymers as gate dielectrics. Journal of the American Chemical Society, 127(29), 10388-10395. [3] Hung, C. C., Wu, H. C., Chiu, Y. C., Tung, S. H., & Chen, W. C. (2016). Crosslinkable high dielectric constant polymer dielectrics for low voltage organic field‐effect transistor memory devices. Journal of Polymer Science Part A: Polymer Chemistry, 54(19), 3224-3236. This research was supported by Nano·Material Technology Development Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT and Future Planning (2016M3A7B4905609) Figure 1

High dielectric constant dipolar glass polymer based on sulfonylated poly(ether ether ketone)

In this work, a new kind of dipolar glass polymer, containing strongly polar sulfonyl groups, was synthesized by post functionalization of the corresponding poly(ether ether ketone) containing carboxyl groups (PEEK-COOH). The sulfonylated PEEK (PEEK-SO2) exhibited strong β transition at −100 °C and 1 Hz due to the large dipole moment (4.25 D) of the side-chain sulfonyl groups, which were attached to the backbone via flexible ester bonds. Because of this strong β dipole relaxation, the glassy PEEK-SO2 exhibited a high dielectric constant of 5.0 at 25 °C and 1 Hz, nearly 32% higher than that of PEEK-COOH. From an electric displacement-electric field loop study, PEEK-SO2 exhibited a relative high discharge energy density of 2.35 J/cm3 at 300 MV/m and room temperature, which was 1.4 times that of PEEK-COOH. However, the hysteresis loss was only 0.008 at 100 Hz and 25 °C. This work further reveals that dipolar glass polymers with high mobile dipolar side groups are suitable for high energy density and low loss dielectric applications.

High dielectric constant composites controlled by a strontium titanate barrier layer on carbon nanotubes towards embedded passive devices

To solve the conundrum of percolative dielectric composites, namely, large dielectric loss caused by direct contact between conductive fillers near the percolation threshold, researchers introduced a general method of coating an insulative shell on the conductive fillers. In this work, a core–shell-structured hybrid is synthesized by coating strontium titanate (STO) shell onto the multiwalled carbon nanotubes (MWCNTs) via sol–gel processing and compounded with epoxy resin as conductive filler to prepared the high dielectric constant percolative polymer composites. The STO shell outside the MWCNTs constrained the electrical conductivity of MWCNTs as an insulating layer and increased the dielectric constant of composites as a high dielectric constant ceramic. According to the dual function of STO shell, the composites of STO-coated MWCNTs and epoxy resin show an effectively improved dielectric constant and significantly reduced the dielectric loss. In the case of low filler loading amount at 11 wt%, the dielectric constant of the composite can reach 283 at 1000 Hz, and the dielectric loss is only 0.07.

Polymer multilayer films for high temperature capacitor application

ABSTRACTAdvanced film capacitors require polymers with high thermal stability, high breakdown strength, and low loss for high temperature dielectric applications. To fulfill such requirements, two polymer multilayer film systems were coextruded via the forced assembly technique. High glass transition temperature (T g) polycarbonate (HTPC, Tg = 165 °C) and polysulfone (PSF, Tg = 185 °C) were multilayered with a high dielectric constant polymer, poly(vinylidene fluoride) (PVDF), respectively. The PSF/PVDF system was more thermally stable than the HTPC/PVDF system because of the higher Tg for PSF. At temperatures lower than 170 °C, the HTPC/PVDF system exhibited comparable breakdown strength and hysteresis loss as the PSF/PVDF system. While at temperatures above 170 °C, the PSF/PVDF system exhibited a higher breakdown strength because of the higher Tg of PSF. The electric displacement‐electric field (D‐E) loop behavior of the PSF/PVDF system was studied as a function of temperature. Moreover, a melt‐recrystallization process could further decrease the hysteresis loss for the PSF/PVDF system due to better edge‐on crystal orientation. These results demonstrate that PSF/PVDF and HTPC/PVDF systems are applicable for high temperature film capacitors. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47535.

Effects of Polymer Coatings on Electrodeposited Lithium Metal.

The electrodeposition of lithium metal is a key process in next-generation, high energy density storage devices. However, the high reactivity of the lithium metal causes short cycling lifetimes and dendrite growth that can pose a serious safety issue. Recently, a number of approaches have been pursued to stabilize the lithium metal-electrolyte interface, including soft polymeric coatings that have shown the ability to enable high-rate and high-capacity lithium metal cycling, but a clear understanding of how to design and modify these coatings has not yet been established. In this work, we studied the effects of several polymers with systematically varied chemical and mechanical properties as coatings on the lithium metal anode. By examining the early stages of lithium metal deposition, we determine that the morphology of the lithium particles is strongly influenced by the chemistry of the polymer coating. We have identified polymer dielectric constant and surface energy as two key descriptors of the lithium deposit size. Low surface energy polymers were found to promote larger deposits with smaller surface areas. This may be explained by a reduced interaction between the coating and the lithium surface and thus an increase in the interfacial energy. On the other hand, high dielectric constant polymers were found to increase the exchange current and gave larger lithium deposits due to the decreased overpotentials at a fixed current density. We also observed that the thickness of the polymer coating should be optimized for each individual polymer. Furthermore, polymer reactivity was found to strongly influence the Coulombic efficiency. Overall, this work offers new fundamental insights into lithium electrodeposition processes and provides direction for the design of new polymer coatings to better stabilize the lithium metal anode.

High Dielectric Constant Sulfonyl-Containing Dipolar Glass Polymers with Enhanced Orientational Polarization

Dipolar glass (DG) polymers, which utilize sub-Tg orientational polarization (Tg is the glass transition temperature) to enhance dielectric constants, are promising candidates for use in advanced e...

High Performance Low Dielectric Constant Polymer with Good Film‐Forming Ability Developed from Renewable Plant Oil (Anethole)

AbstractA new polymer showing low dielectric constant and good film‐forming ability derived from a renewable plant oil (anethole) and thermo cross‐linkable benzocyclobutene is developed. This polymer with anethole content of more than 50% is prepared through a thermal cross‐linking reaction of an anethole‐based monomer with active benzocyclobutene unit, and it displays a low dielectric constant of less than 2.70 varying from 0.1 to 30 MHz, low water uptake of below 0.1%, and good thermostability (5% weight loss of up to 430 °C). The polymer film also exhibits high transparency and low surface roughness. These results are comparable to that of the commercial benzocyclobutene‐based high performance polymers widely used in electronic/microelectronic industry, suggesting that the renewable anethole could be considered as a new sustainable feedstock supply to produce the benzocyclobutene‐like high performance materials.

Rational Design and Modification of High-k Bis(double-stranded) Block Copolymer for High Electrical Energy Storage Capability

High dielectric constant (high-k) polymers have important application in advanced electronic devices such as energy storage, wearable electronics, artificial muscles, and electrocaloric cooling because of their excellent flexibility and ease of processing. However, most of the commercially available polymers have low-k values and the designed strategies for enhancing k are usually at the cost of the increase of dielectric loss. In this work, novel high-k and low loss bis(double-stranded) block copolymers, containing the ionic-conjugated hybrid conductive segments (HCS) with narrow band gap and the insulating segments with wide band gap, were synthesized by tandem metathesis polymerizations. The novel copolymers exhibited enhanced dielectric constant of 33–28 accompanied by low dielectric loss of 0.055–0.02 at 102–106 Hz, and thus greatly increased stored energy density of 9.95 J cm–3 was achieved at relatively low electric field of 370 MV m–1, which is significantly higher than that of the commercial biax...

Achieving Relaxor Ferroelectric-like Behavior in Nylon Random Copolymers and Terpolymers

High dielectric constant polymers, exhibiting relaxor ferroelectric (RFE) behaviors (i.e., slim single and double hysteresis loops, SHLs and DHLs), are attractive for high energy density and low loss dielectric applications. Utilizing the principle of nanosized ferroelectric domains (nanodomains), this study has designed and developed novel RFE-like polyamides (PAs) based on 11-aminoundecanoic acid, 12-aminododecanoic acid, and N-methyl-11-aminoundecanoic acid (NM11) as an alternative to the high-cost and difficult-to-synthesize poly(vinylidene fluoride) (PVDF)-based RFE polymers. In the first attempt, quenched and stretched (QS) PA(11-co-12) copolymers exhibited enhanced ferroelectricity as compared with either nylon-11 or nylon-12. Although relatively narrow hysteresis loops could be achieved at 75 °C, the hydrogen-bonding interaction was not weak enough to induce nanodomains in the nylon copolymers. To further reduce the hydrogen-bonding interaction and achieve nanodomains, a PA(11-co-12-co-NM11) 30/60...

Multiple Interfacial Fe3O4@BaTiO3/P(VDF-HFP) Core-Shell-Matrix Films with Internal Barrier Layer Capacitor (IBLC) Effects and High Energy Storage Density.

Flexible nanocomposites composed of high dielectric constant fillers and polymer matrix have shown great potential for electrostatic capacitors and energy storage applications. To obtain the composited material with high dielectric constant and high breakdown strength, multi-interfacial composited particles, which composed of conductive cores and insulating shells and possessed the internal barrier layer capacitor (IBLC) effect, were adopted as fillers. Thus, Fe3O4@BaTiO3 core-shell particles were prepared and loaded into the poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) polymer matrix. As the mass fraction of core-shell fillers increased from 2.5 wt % to 30 wt %, the dielectric constant of the films increased, while the loss tangent remained at a low level (<0.05 at 1 kHz). Both high electric displacement and high electric breakdown strength were achieved in the films with 10 wt % core-shell fillers loaded. The maximum energy storage density of 7.018 J/cm3 was measured at 2350 kV/cm, which shows significant enhancement than those of the pure P(VDF-HFP) films and analogous composited films with converse insulating-conductive core-shell fillers. A Maxwell-Wagner capacitor model was also adopted to interpret the efficiency of IBLC effects on the suppressed loss tangent and the superior breakdown strength. This work explored an effective approach to prepare dielectric nanocomposites for energy storage applications experimentally and theoretically.

Embedded nonlinear passive components on flexible substrates for microelectronics applications

This paper describes nonlinear dielectric composite passive components on flexible metallic substrates for transient protection of electronic devices, most notably against electrostatic discharge (ESD) and electrical overstress (EOS) conditions. In this case, the passive device comprises a polymer composite that contains nonlinear inorganic fillers, an electric field switchable dielectric ceramic Calcium Copper Titanate (CaCu3Ti4O12, CCT), in a metal insulator metal (MIM) configuration. Compatibility with PCB (printed circuit board) in line processing is demonstrated since the fabrication process described is a relatively low temperature process. Advantageously, the construction of such components are such that they can be embedded within a PCB (printed circuit board), thereby allowing miniaturization of the circuit design and can potentially be adopted in an industrial roll to roll manufacturing process. The dielectric characteristics of the CCT filler polymer composites are compared with well-known high dielectric constant Barium Titanate filler polymer composites for capacitor applications. Theoretical models based on effective medium theory are used to predict the dielectric properties of the CCT epoxy composites as a function of filler loading fractions. Maxwell Garnett model was found to provide the best fit to experimental data.

50th Anniversary Perspective: Dielectric Phenomena in Polymers and Multilayered Dielectric Films

High dielectric constant and low dielectric loss are desirable electrical properties for next-generation polymer dielectrics that show promise for applications in pulsed power, power electronics, and printable electronics. Unfortunately, the dielectric constant of polymers is often limited to 2–5, much lower than that of inorganic dielectrics, because of the nature of hydrocarbon covalent bonds for electronic and atomic polarizations. It is essential to understand the fundamental physics of different types of polarization and the associated loss mechanisms in polymers. In this Perspective, we discuss the characteristics of each polarization and explain how to enhance the polarization using rational molecular designs without causing significant dielectric losses. Among various approaches for high dielectric constant and low loss polymers, the multilayer film technology is of particular interest because a multilayer film is a unique one-dimensional system with tailored material choices, layer thicknesses, a...

Synthesis and properties of a high dielectric constant copolymer of a copper phthalocyanine oligomer grafted to amino-capped polyimide

A novel high dielectric constant all-organic polymer film of a copper phthalocyanine oligomer grafted to polyimide (CuPc–PI) was successfully synthesized via a polycondensation between a copper phthalocyanine anhydride oligomer and amino-capped polyamic acid, followed by thermal treatment.

Achieving large dielectric property improvement in polymer/carbon nanotube composites by engineering the nanotube surface via atom transfer radical polymerization

High dielectric constant (high-k) polymer composites have many applications in electrical insulation and energy storage systems because of their ease of processing. An important route to high-k polymer composites is to introduce high-aspect-ratio conductive nanoparticles (e.g., carbon nanotubes, CNTs) into a dielectric polymer. However, it is difficult to tune the dielectric properties of the composites via only adjusting the nanoparticle loading, particularly when the conductive nanoparticle concentration is near the percolation threshold. In this work, by using surface-initiated atom transfer radical polymerization, poly(methyl methacrylate) encapsulated CNTs (PMMA@CNTs) were prepared and used to tune the dielectric properties of PMMA composites. It was found that the PMMA@CNTs can be well dispersed into the PMMA matrix, regardless of the thickness of the PMMA shell grafted onto the CNT surface. The electrical parameters of the composites, such as percolation threshold, electrical conductivity, dielectric constant and dielectric loss tangent, can be tuned by controlling the thickness of the PMMA shell on the CNT surface. High dielectric constant and low dielectric loss can be achieved by adjusting the loading of PMMA@CNTs and the thickness of the PMMA shell on the CNT surface.

Tailoring Dielectric Properties and Energy Density of Ferroelectric Polymer Nanocomposites by High-k Nanowires.

High dielectric constant (k) polymer nanocomposites have shown great potential in dielectric and energy storage applications in the past few decades. The introduction of high-k nanomaterials into ferroelectric polymers has proven to be a promising strategy for the fabrication of high-k nanocomposites. One-dimensional large-aspect-ratio nanowires exhibit superiority in enhancing k values and energy density of polymer nanocomposites in comparison to their spherical counterparts. However, the impact of their intrinsic properties on the dielectric properties of polymer nanocomposites has been seldom investigated. Herein, four kinds of nanowires (Na2Ti3O7, TiO2, BaTiO3, and SrTiO3) with different inherent characteristics are elaborately selected to fabricate high-k ferroelectric polymer nanocomposites. Dopamine functionalization facilitates the excellent dispersion of these nanowires in the ferroelectric polymer matrix because of the strong polymer/nanowire interfacial adhesion. A thorough comparative study on the dielectric properties and energy storage capability of the nanowires-based nanocomposites has been presented. The results reveal that, among the four types of nanowires, BaTiO3 NWs show the best potential in improving the energy storage capability of the proposed nanocomposites, resulting from the most signficant increase of k while retaining the rather low dielectric loss and leakage current.

Exploring Strategies for High Dielectric Constant and Low Loss Polymer Dielectrics.

Polymer dielectrics having high dielectric constant, high temperature capability, and low loss are attractive for a broad range of applications such as film capacitors, gate dielectrics, artificial muscles, and electrocaloric cooling. Unfortunately, it is generally observed that higher polarization or dielectric constant tends to cause significantly enhanced dielectric loss. It is therefore highly desired that the fundamental physics of all types of polarization and loss mechanisms be thoroughly understood for dielectric polymers. In this Perspective, we intend to explore advantages and disadvantages for different types of polarization. Among a number of approaches, dipolar polarization is promising for high dielectric constant and low loss polymer dielectrics, if the dipolar relaxation peak can be pushed to above the gigahertz range. In particular, dipolar glass, paraelectric, and relaxor ferroelectric polymers are discussed for the dipolar polarization approach.

High‐Dielectric Constant Side‐Chain Polymers Show Reduced Non‐Geminate Recombination in Heterojunction Solar Cells

High-dielectric constant side-chain polymers that show reduced non-geminate recombination in heterojunction solar cells are reported. Active layer polymers with high dielectric side-chains show increased performance over alkyl side-chain polymers. The doubling in efficiency is attributed to suppressed recombination. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Core–satellite Ag@BaTiO3 nanoassemblies for fabrication of polymer nanocomposites with high discharged energy density, high breakdown strength and low dielectric loss

Dielectric polymer nanocomposites with high dielectric constant have wide applications in high energy density electronic devices. The introduction of high dielectric constant ceramic nanoparticles into a polymer represents an important route to fabricate nanocomposites with high dielectric constant. However, the nanocomposites prepared by this method generally suffer from relatively low breakdown strength and high dielectric loss, which limit the further increase of energy density and energy efficiency of the nanocomposites. In this contribution, by using core-satellite structured ultra-small silver (Ag) decorated barium titanate (BT) nanoassemblies, we successfully fabricated high dielectric constant polymer nanocomposites with enhanced breakdown strength and lower dielectric loss in comparison with conventional polymer-ceramic particulate nanocomposites. The discharged energy density and energy efficiency are derived from the dielectric displacement-electric field loops of the polymer nanocomposites. It is found that, by using the core-satellite structured Ag@BT nanoassemblies as fillers, the polymer nanocomposites can not only have higher discharged energy density but also have high energy efficiency. The mechanism behind the improved electrical properties was attributed to the Coulomb blockade effect and the quantum confinement effect of the introduced ultra-small Ag nanoparticles. This study could serve as an inspiration to enhance the energy storage densities of dielectric polymer nanocomposites.