Electrical Conduction and Carrier Traps in Polymeric Materials

Ieda, Masayuki

doi:10.1109/tei.1984.298741

Cited by 266 publications

(117 citation statements)

References 87 publications

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“…Using our data we then obtain a prefactor 0 Ϸ750 cm 2 /V s and an excess electron mobility of Ϸ2ϫ10 Ϫ3 cm 2 /V s. Note that the present energy resolution produces an uncertainty in the mobility of about one order of magnitude ͑due to the exponential factor͒. This value compares favorably with the reported values in PE, which is in the range 10 Ϫ3 -10 Ϫ10 cm 2 /V s. 68 It has been suggested 69 that the striking range of variation of the mobility values reported by various investigators is mainly due to the different measurement procedures adopted, and in particular to the measurement time for each particular experiment. When the conduction takes place over very long times, carrier trapping and therefore space charge formation become dominant, providing the lowest values of the apparent mobility.…”

Section: Amorphous Pesupporting

confidence: 78%

Electronic transport in disordered n-alkanes: From fluid methane to amorphous polyethylene

Cubero

Quirke

Coker

2003

The Journal of Chemical Physics

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We use a fast Fourier transform block Lanczos diagonalization algorithm to study the electronic states of excess electrons in fluid alkanes ͑methane, ethane, and propane͒ and in a molecular model of amorphous polyethylene ͑PE͒ relevant to studies of space charge in insulating polymers. We obtain a new pseudopotential for electron-PE interactions by fitting to the electronic properties of fluid alkanes and use this to obtain new results for electron transport in amorphous PE. From our simulations, while the electronic states in fluid methane are extended throughout the whole sample, in amorphous PE there is a transition between localized and delocalized states slightly above the vacuum level ͑ϳϩ0.06 eV͒. The localized states in our amorphous PE model extend to Ϫ0.33 eV below this level. Using the Kubo-Greenwood equation we compute the zero-field electron mobility in pure amorphous PE to be Ϸ2ϫ10Ϫ3 cm 2 /V s. Our results highlight the importance of electron transport through extended states in amorphous regions to an understanding of electron transport in PE.

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Section: Amorphous Pesupporting

confidence: 78%

Electronic transport in disordered n-alkanes: From fluid methane to amorphous polyethylene

Cubero

Quirke

Coker

2003

The Journal of Chemical Physics

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“…To understand the sandwich-structured nanocomposites with different layer arrangements, it is informative to investigate the conduction mechanisms of its components, i.e., c-BCB/BNNS and c-BCB/BT, under elevated temperatures. Several conduction mechanisms exist in polymeric materials, including the hopping conduction, the Schottky charge injection (thermionic emission) and the PooleFrenkel (P-F) emission (20,25). Hopping conduction is commonly observed in amorphous polymers such as c-BCB, as we previously demonstrated (8).…”

Section: Discussionmentioning

confidence: 74%

Sandwich-structured polymer nanocomposites with high energy density and great charge–discharge efficiency at elevated temperatures

Liu

Yang

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

350

202

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The demand for a new generation of high-temperature dielectric materials toward capacitive energy storage has been driven by the rise of high-power applications such as electric vehicles, aircraft, and pulsed power systems where the power electronics are exposed to elevated temperatures. Polymer dielectrics are characterized by being lightweight, and their scalability, mechanical flexibility, high dielectric strength, and great reliability, but they are limited to relatively low operating temperatures. The existing polymer nanocomposite-based dielectrics with a limited energy density at high temperatures also present a major barrier to achieving significant reductions in size and weight of energy devices. Here we report the sandwich structures as an efficient route to high-temperature dielectric polymer nanocomposites that simultaneously possess high dielectric constant and low dielectric loss. In contrast to the conventional single-layer configuration, the rationally designed sandwich-structured polymer nanocomposites are capable of integrating the complementary properties of spatially organized multicomponents in a synergistic fashion to raise dielectric constant, and subsequently greatly improve discharged energy densities while retaining low loss and high charge-discharge efficiency at elevated temperatures. At 150°C and 200 MV m −1 , an operating condition toward electric vehicle applications, the sandwich-structured polymer nanocomposites outperform the state-of-the-art polymer-based dielectrics in terms of energy density, power density, charge-discharge efficiency, and cyclability. The excellent dielectric and capacitive properties of the polymer nanocomposites may pave a way for widespread applications in modern electronics and power modules where harsh operating conditions are present.electrical energy storage | dielectric | polymer nanocomposites | capacitors | high temperature F ilm capacitors store electrical energy in dielectric materials in the form of an electrostatic field between two electrodes. They possess the highest power density (on the order of megawatts) and the best rate capability (on the order of microseconds) among the electrical energy storage devices and are critical for power electronics, power conditioning, and pulsed power applications (1-3). For instance, DC bus capacitors are essential components in the power inverters of electric vehicles for the conversion of direct current to alternating current, which is required to drive the vehicle's motor. Compared with ceramics, polymeric materials offer inherent advantages for capacitors, including their light weight, facile processability, scalability, high breakdown strength, and graceful failure mechanism (1-5). However, dielectric polymers often suffer from low operating temperatures, which fall short of the emerging demands for energy storage and conversion in harsh environments commonly present in automobile, aerospace power systems, and advanced microelectronics (6, 7). For example, to accommodate biaxially oriented polypropylen...

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“…However, it is noteworthy that a systemic study on high field electrical conduction of polymeric nanocomposite is still lack; especially the characteristics of charge transportation and conduction under a high electrical field have rarely been reported. It is well known that microscopic structures, such as the density, crystallinity of a composite, the size of the filler and the morphology of interfaces between the polymer matrix and the filler, have great effects on the electrical conduction in the composite (6)- (9) . Conduction current measurement in insulating materials have been confirmed to be a significant way that it not only provides fundamental data for commercial application, but also obtains complementary information on the processes of charge injection, transportation and conduction mechanism, which is very helpful to understand the relationship between chemical-physical-microstructure and electrical properties, and propose theoretical instruction to design and develop a new material (10) .…”

Section: Introductionmentioning

confidence: 99%

High Field Electrical Conduction in the Nanocomposite of Low-density Polyethylene and Nano-SiOX

et al. 2006

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In order to determine how inorganic nano-powder affects the high-electric-field conduction in the nanocomposite, a method of double-solution mixture was used to prepare nanocomposites containing various nano-SiO x contents. Molecular structure and morphology of a composite of low-density polyethylene (LDPE) and nano-SiO x were studied by dynamic mechanical analysis (DMA). The storage modulus (E / ) and the glass transition temperature (T g ) of the composite are higher than those of pure polyethylene and vary with nano-SiO x contents in U-shapes. The effect of the content of nano-SiO x on Tg is shown in Table 1. High field electrical conduction of samples with and without nano-SiO x was investigated in the range of 293K~353K and the results are shown in Fig. 1 (a) and (b), respectively. It could be seen that the high electrical field conduction in the composite containing 1.0 wt% nano-SiOx is not the same as that in pure LDPE, which suggests that the model describing the high field electrical conduction of the nanocomposite might not be the same as that describing pure LDPE. Slopes of high field electrical conduction currents for pure LDPE in log-log plot are in the range of 2.11~2.78 at the testing temperatures. It could be thought that space-charge-limited current (SCLC) must be the main conduction for LDPE, which is the same conclusion as other researchers have drawn. However, slopes for the nanocomposite are larger than 4.0, which could not be explained with SCLC model. In order to know the proper model describing the high-electric-field conduction in the nanocomposite, Schottky effect and Poole-Frenkel effect are used to fit for our data. Unfortunately, both models could not well explain the high field electrical conduction of the nanocomposite.Finally, we found that ionic hopping conduction model could be used to explain our data very well. It also found the average hopping distance for the composite containing 1wt% nano-SiO x shifts from 4.3 to 4.7 nm as the temperature increases from 293K to 353K. Non-memberMolecular structure and morphology of a nanocomposite of low-density polyethylene (LDPE) and nano-SiO x were studied by dynamic mechanical analysis (DMA). The storage modulus (E / ) and the glass transition temperature (T g ) of the nanocomposite are higher than those of pure LDPE and vary with nano-SiO x contents in U-shapes. High field electrical conduction in the nanocomposite was investigated in the range of 293K~353K, which is consistent with a theory based on the conventional thermally activated ionic hopping conduction. The average hopping distance for the nanocomposite containing 1wt % nano-SiO x shifts from 4.3 to 4.7 nm as the temperature increases from 293K to 353K. Space charge distribution was taken to confirm ionic hopping conduction being the dominant one in the nanocompostie. It is interesting that the relationship between nano-SiO x content and DC conduction was similar to a percolation conduction existing in a composite of conductive particles (or semi conductive particles) and a p...

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Electrical Conduction and Carrier Traps in Polymeric Materials

Cited by 266 publications

References 87 publications

Electronic transport in disordered n-alkanes: From fluid methane to amorphous polyethylene

Electronic transport in disordered n-alkanes: From fluid methane to amorphous polyethylene

Sandwich-structured polymer nanocomposites with high energy density and great charge–discharge efficiency at elevated temperatures

High Field Electrical Conduction in the Nanocomposite of Low-density Polyethylene and Nano-SiOX

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