Nanocomposite Dielectric Films Research Articles

Photo‐Curable Stretchable High‐k Polymer/TiO2 Nanosheet Hybrid Dielectrics for Field‐Effect Transistors

Elastomeric polymer materials are of interest due to their stretchability, low‐temperature processing, and scalability. In addition, the incorporation of 2D materials can further enhance the dielectric properties and capacitance of elastic polymer materials, thereby reducing the driving voltage and energy consumption. In this study, titanium dioxide (TiO2) nanosheets are cross‐linked with nitrile butadiene rubber using thiol‐ene click chemistry, which leads to the preparation of nanocomposite dielectric films with stretchability and high dielectric constant. Furthermore, by controlling the doping amount of the nanosheets, it is observed that the capacitance of the nanocomposite films increases from 25.61 to 684.67 nF cm−2, and the dielectric constant increases from 14.96 to 161.98. Finally, the stretchable nanocomposite films exhibit good insulating properties even at 50% strain. In this study, insight is provided into the potential of in situ cross‐linking between elastic polymer materials and 2D materials to produce high‐k dielectric materials with both stretchability and high insulating properties.

Polypropylene nanocomposite film with enhanced energy storage performance via a continuous preparation

Dielectric polymers have been extensively employed in renewable energy conversion, hybrid electric vehicle, and high voltage direct current transmission systems, owing to their excellent electrical insulation, processability, and self-healing capability. However, the challenge lies in their relatively low dielectric constant (εr) and limited discharge energy density (Ue), which hinder the advancement of integrated power modules. Despite numerous efforts aimed at enhancing Ue, the fabrication of scalable dielectric film with both enhanced Ue and high charge–discharge efficiency (η) remains a major obstacle. Herein, the polypropylene-based films with BaTiO3@PP-g-MAH (BTO@PP-g-MAH) core–shell nanoparticles are prepared through a continuous melt extrusion process. The resulting nanocomposite film, incorporated with 5 wt% BTO@PP-g-MAH, exhibits an impressive Ue of 5.15 J cm−3 and achieves a high η of 93.2 % at 433 MV m−1, along with excellent cycle dielectric stability. Such enhancements in εr and Ue are ascribed to the improved interfacial polarization facilitated by BaTiO3 nanoparticles and the enhanced interface binding achieved through the PP-g-MAH shell layers. Furthermore, the enhancement of electric breakdown strength (Eb) is comprehensively investigated based on electrical breakdown mechanism and electromechanical breakdown model. This study demonstrates a novel strategy to prepare nanocomposite dielectric films that are compatible with commercial capacitor fabrication process.

Core-shell structure polydopamine and polyethylenimine co-assisted MoS2-BaTiO3/polyarylene ether nitrile nanocomposites for high-temperature resistant organic dielectrics

In this work, a novel nanoparticle ((MoS2-BT)@(PDA+PEI)) was constructed through two-dimensional molybdenum disulfide (MoS2) and zero-dimensional barium titanate (BT) via in-situ polymerization and co-modification of polydopamine (PDA) and polyethylenimine (PEI). Then the nanofillers were dispersed in the Polyarylene ether nitrile (PEN) matrix by film casting to obtain PEN/(MoS2-BT)@(PDA+PEI) nanocomposite dielectric films. Subsequently, the latter were subjected to chemical crosslinking at high temperature to obtain CPEN/(MoS2-BT)@(PDA+PEI) nanocomposites. The effects of filler content on the properties of PEN matrix composite films were investigated. The results indicate excellent compatibility between (MoS2-BT)@(PDA+PEI) and the PEN matrix due to the introduction of an organic modification layer, resulting in overall good performance of nanocomposite films, including good thermal stability with a glass transition temperature (Tg) exceeding 240 °C after chemical crosslinking. The dielectric constant of CPEN nanocomposites containing 40wt% of the hybrid nanoparticles is 20.2 and the dielectric loss is 0.032 at 1kHz, the dielectric constant-temperature coefficient of all CPEN nanocomposites is less than 6×10-4 °C-1 at the temperature range of 25-220 °C. In short, the incorporation of (MoS2-BT)@(PDA+PEI) effectively enhances the thermal, mechanical, and dielectric properties of PEN-based nanocomposites.

Enhanced Thermal and Dielectric Properties of Polyarylene Ether Nitrile Nanocomposites Incorporated with BN/TiO2-Based Hybrids for Flexible Dielectrics.

Outstanding high-temperature resistance, thermal stability, and dielectric properties are fundamental for dielectric materials used in harsh environments. Herein, TiO2 nanoparticles are decorated on the surface of BN nanosheets by internal crosslinking between polydopamine (PDA) and polyethyleneimine (PEI), forming three-dimensional novel nanohybrids with a rough surface. Then, an ether nitrile (PEN) matrix is introduced into the polyarylene to form polymer-based nanocomposite dielectric films. Meanwhile, the structure and micromorphology of the newly prepared nanohybrids, as well as the dielectric and thermal properties of PEN nanocomposites, are investigated in detail. The results indicate that TiO2 nanoparticles tightly attach to the surface of BN, creating a new nanohybrid that significantly enhances the comprehensive performance of PEN nanocomposites. Specifically, compared to pure PEN, the nanocomposite film with a nanofiller content of 40 wt% exhibited an 8 °C improvement in the glass transition temperature (Tg) and a 162% enhancement in the dielectric constant at 1 kHz. Moreover, the dielectric constant-temperature coefficient of the nanocomposite films remained below 5.1 × 10-4 °C-1 within the temperature range of 25-160 °C, demonstrating excellent thermal resistance. This work offers a method for preparing highly thermal-resistant dielectric nanocomposites suitable for application in elevated temperature environments.

Nanocomposite Dielectric Films with Interphasic Response from Olefin Metathesis of Functionalized HfO2 Nanocrystals

Nanocomposite Dielectric Films with Interphasic Response from Olefin Metathesis of Functionalized HfO₂ Nanocrystals

Enhanced breakdown strength of the BaTiO3/polypropylene nanocomposite film based on the biaxial stretching process

AbstractThe significant progresses of polymer‐based nanocomposites with improved dielectric performances are urgently calling for an effect way to realise commercial production. Up to now, the biaxial stretching technology is still a powerful method to produce the high‐performance dielectric films applied in the film capacitors due to its full‐blown applications. In this work, a classical composite system of BaTiO3/polypropylene was applied to reveal the connection between the microstructure changes and dielectric properties of the corresponding nanocomposite films in the biaxial stretching process. The permittivity of BT‐30 wt% nanocomposite reached 2.8 at 103 Hz after stretching, and its breakdown strength reached 340 MV/m. In addition, the breakdown strength of BT‐10 wt% nanocomposite could even be promoted to 452 MV/m, which was 1.3 times higher than that before stretching. The microstructure test demonstrated that the rearrangement of nanofillers, high crystallinity and the oriented polypropylene crystals were advantageous to the improvement of breakdown strength for the stretched nanocomposite films. Therefore, the application of biaxial stretching technology into the preparation of nanocomposite dielectric film is an enormous potential way for the energy storage film capacitors.

Structural evolution and dielectric properties of biaxially oriented polyethylene/multiwalled carbon nanotube composite films.

In modern power systems, polymer nanocomposite films have been more frequently used as dielectric materials for capacitors. However, the low energy storage density limits its application in more areas. It is a very challenging task to prepare dielectric films with high dielectric constant (ε), high energy storage density, and low dielectric loss (tan δ) at the same time. In this study, one kind of BOPE (biaxially oriented polyethylene) nanocomposite dielectric films with a very small amount of MWCNTs (multiwalled carbon nanotubes) was reported. MWCNTs with a high aspect ratio were used for conductive filler, and the formation of more micro capacitors and interfacial polarization were caused by better dispersibility of MWCNTs in polyethylene matrix by biaxial stretching. The BOPE/MWCNT composite films with high-performance were successfully prepared by achieving the requirements of low content, high dielectric constant and high energy storage density while maintaining the advantages of low dielectric loss of the polymer matrix. The dielectric constant of the BOPE/MWCNT composite films increased from 2.26 to 4.68 with the drawing ratio was 4 × 4 and the content of MWCNTs was 0.6 wt% and the energy storage density was also increased from 1.01 J cm−3 to 1.29 J cm−3. From our work, the achievement of low thickness, high energy density and low loss at the same time implied BOPE/MWCNT composite films were promising materials for next-generation film capacitors.

Enhanced Dielectric Permittivity of Optimized Surface Modified of Barium Titanate Nanocomposites.

High permittivity polymer-ceramic nanocomposite dielectric films take advantage of the ease of flexibility in processing of polymers and the functionality of electroactive ceramic fillers. Hence, films like these may be applied to embedded energy storage devices for printed circuit electrical boards. However, the incompatibility of the hydrophilic ceramic filler and hydrophobic epoxy limit the filler concentration and therefore, dielectric permittivity of these materials. Traditionally, surfactants and core-shell processing of ceramic fillers are used to achieve electrostatic and steric stabilization for adequate ceramic particle distribution but, questions regarding these processes still remain. The purpose of this work is to understand the role of surfactant concentration ceramic particle surface morphology, and composite dielectric permittivity and conductivity. A comprehensive study of barium titanate-based epoxy nanocomposites was performed. Ethanol and 3-glycidyloxypropyltrimethoxysilan surface treatments were performed, where the best reduction in particle agglomeration, highest value of permittivity and the lowest value of loss were observed. The results demonstrate that optimization of coupling agent may lead to superior permittivity values and diminished losses that are ~2–3 times that of composites with non-optimized and traditional surfactant treatments.

Studying of SiO2/capron nanocomposite as a gate dielectric film for improved threshold voltage

In this study, SiO2 gate dielectric operation was improved using SiO2/capron nanocomposite. SiO2/capron nanocomposite was synthesized by the sol–gel method. The existence of two phases in the nanocomposite structure was revealed using energy dispersive spectroscopy. The formation of hydrogen bonds among SiO2 nanofillers and capron matrix was proved by Fourier transform infrared spectroscopy and thermogravimetric analysis. The fact resulted in the uniform dispersion of SiO2 nanoparticles within capron matrix and the formation of cross-linked network. Pure SiO2, pure capron, SiO2/capron nanocomposite dissolved in benzene alcohol and SiO2/capron nanocomposite dissolved in acid formic as the gate dielectric films were deposited on the p-type Si substrates. Atomic force microscopy showed a significant decrease in the average surface roughness of nanocomposite film (0.02 nm) compared to that of pure SiO2 and pure capron films (18.3 and 7.85 nm, respectively). The operation of deposited films as the gate dielectrics was compared by the current–voltage (I–V) measurements in the metal–insulator–semiconductor structure. Fabricated p-type Si field-effect-transistors demonstrated a great decrease in the leakage currents and the threshold voltages by decreasing the surface roughness of their dielectric films, because the charge transport is strongly associated with trap depth and carrier scattering effects in the semiconductor/dielectric interface. As a result, the threshold voltages were shifted toward downward and reached 1 V for transistor based on SiO2/capron nanocomposite dielectric film.

Synthesis and characterization of silanized-SiO2/povidone nanocomposite as a gate insulator: The influence of Si semiconductor film type on the interface traps by deconvolution of Si2s

The polymer nanocomposite as a gate dielectric film was prepared via sol-gel method. The formation of cross-linked structure among nanofillers and polymer matrix was proved by Fourier transform infrared spectroscopy (FT-IR). Differential thermal analysis (DTA) results showed significant increase in the thermal stability of the nanocomposite with respect to that of pure polymer. The nanocomposite films deposited on the p- and n-type Si substrates formed very smooth surface with rms roughness of 0.045 and 0.058 nm respectively. Deconvoluted Si2s spectra revealed the domination of the SiOH hydrogen bonds and SiOSi covalence bonds in the structure of the nanocomposite film deposited on the p- and n-type Si semiconductor layers respectively. The fabricated n-channel field-effect-transistor (FET) showed the low threshold voltage and leakage currents because of the stronger connection between the nanocomposite and n-type Si substrate. Whereas, dominated hydroxyl groups in the nanocomposite dielectric film deposited on the p-type Si substrate increased trap states in the interface, led to the drop of FET operation.

Flexible Regenerated Cellulose/Boron Nitride Nanosheet High-Temperature Dielectric Nanocomposite Films with High Energy Density and Breakdown Strength

Traditional dielectric polymers are nonbiodegradable and nonrenewable petroleum-derived synthetic ones. Here, we report on flexible and 2D nanolayer-structured nanocomposite dielectric films which ...

Structural and dielectric characteristic of povidone–silica nanocomposite films on the Si (n) substrate

The effects of annealing temperatures at 150, 200 and 240 °C were investigated on the povidone–silica nanocomposite film as a gate dielectric. The thermal gravimetric (TGA) and differential thermal (DTA) analyses showed that the decomposition rate of the nanocomposite increased from around 220 °C. The formation of hydrogen and covalent bonds between the elements of nanocomposite was proved via Fourier transform infrared spectroscopy (FTIR). All the films had low root mean square (0.047–0.12 nm) and leakage current densities (1.32 × 10−5–3.95 × 10−8 A/cm2 at 15 V). The results of deconvoluted X-ray photoelectron spectroscopy (XPS) spectra of the O1s orbital indicated that the Si–OH hydrogen bonds dominating the film were not annealed (55.9%). The Si–OH hydrogen bonds decreased (18%) and the Si–O–Si covalent bonds became dominant (80.36%) in the film annealed at 150 °C. The percentage of Si–O–Si bonds decreased by further increasing the temperature (200 °C) and these bonds disappeared in the film annealed at 240 °C. A peak also appeared at the binding energy which is about 1 eV less than that of the Si–O–Si bonds in the films annealed at 200 and 240 °C. The capacitance and leakage current density of fabricated FETs based on nanocomposite dielectric film annealed at 150 and 200 °C decreased. The degradation of cross-linked structure in the dielectric film annealed at 240 °C and the presence of polar Si–OH groups in the nanocomposite dielectric film which was not annealed increased the capacitance and leakage current densities.

Reduction the leakage current through povidone-SiO2 nano-composite as a promising gate dielectric of FETs

In the present study, povidone-SiO2 nano-composite dielectric film was introduced to replace SiO2 gate dielectric film. The organic and inorganic particles homogeneously dispersed in nano-composite film. The structure of nano-composite film was affected by annealing temperatures. By increase in annealing temperature up to 200 °C, wt% of carbon, oxygen and nitrogen increased and wt% of silicon decreased. At 240 °C, the organic phase desorbed and nano-composite structure degraded. The annealing temperature of 150 °C was suitable for adhesion between two phases. The cross-linked structure of dielectric film annealed at 150 °C led to decrease in leakage current.

The low threshold voltage n-type silicon transistors based on a polymer/silica nanocomposite gate dielectric: The effect of annealing temperatures on their operation

In this work, povidone/silica nanocomposite dielectric layers were deposited on the n-type Si (100) substrates for application in n-type silicon field-effect transistors (FET). Thermogravimetric analysis (TGA) indicated that strong chemical interactions between polymer and silica nanoparticles were created. In order to examine the effect of annealing temperatures on chemical interactions and nanostructure properties, annealing process was done at 423–513K. Atomic force microscopy (AFM) images show the very smooth surfaces with very low surface roughness (0.038–0.088nm). The Si2p and C1s core level photoemission spectra were deconvoluted to the chemical environments of Si and C atoms respectively. The obtained results of deconvoluted X-ray photoelectron spectroscopy (XPS) spectra revealed a high percentage of silanol hydrogen bonds in the sample which was not annealed. These bonds were inversed to stronger covalence bonds (siloxan bonds) at annealing temperature of 423K. By further addition of temperature, siloxan bonds were shifted to lower binding energy of about 1eV and their intensity were abated at annealing temperature of 513K. The electrical characteristics were extracted from current-Voltage (I-V) and capacitance-voltage (C-V) measurements in metal-insulator-semiconductor (MIS) structure. The all n-type Si transistors showed very low threshold voltages (−0.24 to 1V). The formation of the strongest cross-linking at nanostructure of dielectric film annealed at 423K caused resulted in an un-trapped path for the transport of charge carriers yielding the lowest threshold voltage (0.08V) and the highest electron mobility (45.01cm2/Vs) for its FET. By increasing the annealing temperature (473 and 513K) on the nanocomposite dielectric films, the values of the average surface roughness, the capacitance and the FET threshold voltage increased and the value of FET electron field-effect mobility decreased.

Fabrication of BaTiO<sub>3</sub>-PMMA Polymer Nanocomposite Thin / Thick Films and their Dielectric Properties

Thin and thick BaTiO3-polymer nanocomposite dielectric films were prepared using BaTiO3 nanoparticles and poly (methyl methacrylate) (PMMA). The cubic BaTiO3 (~ 30-60 nm) and tetragonal BaTiO3 (~ 120 nm) synthesized via hydrothermal/solvothermal route were used as nanofillers. The dielectric constant of 9 was achieved for the films of thicknesses in the 150-300 nm range, which corresponds to a capacitance density of 32 nF/cm2. The dissipation factor of the composite film was of a value of 0.04 at 10 kHz. Thick films (~ 16.3 µm) were prepared by doctor blade method and tested for their capacitance and dielectric properties in the 10-100 kHz frequency range for cubic and tetragonal BaTiO3. The BaTiO3 particles were dispersed homogeneously in the films at lower filler loading. The homogenous distribution of BaTiO3 achieved by surface functionalization of BaTiO3 nanoparticles and use of tetragonal BaTiO3 resulted in the improvement of electric properties of thick and thin films.