The Experts below are selected from a list of 30618 Experts worldwide ranked by ideXlab platform
Qingdong Zheng - One of the best experts on this subject based on the ideXlab platform.
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solution processed bilayer Dielectrics for flexible low voltage organic field effect transistors in pressure sensing applications
Advanced Science, 2018Co-Authors: Zhigang Yin, Ziyang Liu, Mingjie Yin, Yangxi Zhang, Ping A Zhang, Qingdong ZhengAbstract:Flexible pressure sensors based on organic field-effect transistors (OFETs) have emerged as promising candidates for electronic-skin applications. However, it remains a challenge to achieve low operating voltages of hysteresis-free flexible pressure sensors. Interface engineering of polymer Dielectrics is a feasible strategy toward sensitive pressure sensors based on low-voltage OFETs. Here, a novel type of solution-processed bilayer Dielectrics is developed by combining a thick polyelectrolyte layer of polyacrylic acid (PAA) with a thin poly(methyl methacrylate) (PMMA) layer. This bilayer dielectric can provide a vertical phase separation structure from hydrophilic interface to hydrophobic interface which adjoins well to organic semiconductors, leading to improved stability and remarkably reduced leakage currents. Consequently, OFETs using the PMMA/PAA Dielectrics reveal greatly suppressed hysteresis and improved mobility compared to those with a pure PAA dielectric. Using the optimized PMMA/PAA dielectric, flexible OFET-based pressure sensors that show a record high sensitivity of 56.15 kPa-1 at a low operating voltage of -5 V, a fast response time of less than 20 ms, and good flexibility are further demonstrated. The salient features of high capacitance, good dielectric performance, and excellent reliability of the bilayer Dielectrics promise a bright future of flexible sensors based on low-voltage OFETs for wearable electronic applications.
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binary polymer composite Dielectrics for flexible low voltage organic field effect transistors
Organic Electronics, 2018Co-Authors: Ziyang Liu, Zhigang Yin, Shanci Chen, Shilei Dai, Jia Huang, Qingdong ZhengAbstract:Abstract Insulating polymers have been recognized as a promising class of gate Dielectrics for organic field-effect transistors (OFETs). However, the relative permittivity of most single polymer Dielectrics is quite fixed and too low to afford low-operating voltages of OFETs. For flexible low-voltage OFETs, dielectric tunable polymer composites are highly desirable. Here, a new type of binary polymer composite Dielectrics is developed by incorporating a small amount of polyacrylic acid (PAA) into poly(methyl methacrylate) (PMMA) to reduce the operating voltage and enhance the device performance. The resulting dielectric layers deliver a tunable relative permittivity from 3.32 to 4.28 with an increase of PAA contents in the composite. As results, flexible OFETs using PMMA:PAA Dielectrics show greatly improved mobility and reduced threshold voltages with a low-operating voltage below −5 V. The OFETs using the composite dielectric also exhibit excellent performance stability during mechanical bending tests with different radii, where the mobility can maintain 95% of its initial value over 5000 cycles under a bending radius of 5 mm. The tunable dielectric properties and high robustness of these novel Dielectrics make them promising candidates for solution-processed low-voltage flexible OFETs with low power consumption.
Qing Wang - One of the best experts on this subject based on the ideXlab platform.
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sandwich structured polymer nanocomposites with high energy density and great charge discharge efficiency at elevated temperatures
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Feihua Liu, Matthew R. Gadinski, Guangzu Zhang, Tiannan Yang, Longqing Chen, Qing WangAbstract:Abstract 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.
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novel ferroelectric polymers for high energy density and low loss Dielectrics
Macromolecules, 2012Co-Authors: Lei Zhu, Qing WangAbstract:The state-of-the-art polymer Dielectrics have been limited to nonpolar polymers with relatively low energy density but ultralow dielectric losses for the past decades. With the fast development of power electronics in pulsed power and power conditioning applications, there is a need for next-generation dielectric capacitors in areas of high energy density/low loss and/or high temperature/low loss polymer Dielectrics. Given limitations in further enhancing atomic and electronic polarizations for polymers, this Perspective focuses on a fundamental question: Can orientational polarization in polar polymers be utilized for high energy density and low loss Dielectrics? Existing experimental and theoretical results have suggested the following perspectives. For amorphous polar polymers, high energy density and low loss can be achieved below their glass transition temperatures. For liquid crystalline side-chain polymers, dipole mobility is so high that they saturate at relatively low electric fields, and only li...
Ziyang Liu - One of the best experts on this subject based on the ideXlab platform.
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solution processed bilayer Dielectrics for flexible low voltage organic field effect transistors in pressure sensing applications
Advanced Science, 2018Co-Authors: Zhigang Yin, Ziyang Liu, Mingjie Yin, Yangxi Zhang, Ping A Zhang, Qingdong ZhengAbstract:Flexible pressure sensors based on organic field-effect transistors (OFETs) have emerged as promising candidates for electronic-skin applications. However, it remains a challenge to achieve low operating voltages of hysteresis-free flexible pressure sensors. Interface engineering of polymer Dielectrics is a feasible strategy toward sensitive pressure sensors based on low-voltage OFETs. Here, a novel type of solution-processed bilayer Dielectrics is developed by combining a thick polyelectrolyte layer of polyacrylic acid (PAA) with a thin poly(methyl methacrylate) (PMMA) layer. This bilayer dielectric can provide a vertical phase separation structure from hydrophilic interface to hydrophobic interface which adjoins well to organic semiconductors, leading to improved stability and remarkably reduced leakage currents. Consequently, OFETs using the PMMA/PAA Dielectrics reveal greatly suppressed hysteresis and improved mobility compared to those with a pure PAA dielectric. Using the optimized PMMA/PAA dielectric, flexible OFET-based pressure sensors that show a record high sensitivity of 56.15 kPa-1 at a low operating voltage of -5 V, a fast response time of less than 20 ms, and good flexibility are further demonstrated. The salient features of high capacitance, good dielectric performance, and excellent reliability of the bilayer Dielectrics promise a bright future of flexible sensors based on low-voltage OFETs for wearable electronic applications.
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binary polymer composite Dielectrics for flexible low voltage organic field effect transistors
Organic Electronics, 2018Co-Authors: Ziyang Liu, Zhigang Yin, Shanci Chen, Shilei Dai, Jia Huang, Qingdong ZhengAbstract:Abstract Insulating polymers have been recognized as a promising class of gate Dielectrics for organic field-effect transistors (OFETs). However, the relative permittivity of most single polymer Dielectrics is quite fixed and too low to afford low-operating voltages of OFETs. For flexible low-voltage OFETs, dielectric tunable polymer composites are highly desirable. Here, a new type of binary polymer composite Dielectrics is developed by incorporating a small amount of polyacrylic acid (PAA) into poly(methyl methacrylate) (PMMA) to reduce the operating voltage and enhance the device performance. The resulting dielectric layers deliver a tunable relative permittivity from 3.32 to 4.28 with an increase of PAA contents in the composite. As results, flexible OFETs using PMMA:PAA Dielectrics show greatly improved mobility and reduced threshold voltages with a low-operating voltage below −5 V. The OFETs using the composite dielectric also exhibit excellent performance stability during mechanical bending tests with different radii, where the mobility can maintain 95% of its initial value over 5000 cycles under a bending radius of 5 mm. The tunable dielectric properties and high robustness of these novel Dielectrics make them promising candidates for solution-processed low-voltage flexible OFETs with low power consumption.
Longqing Chen - One of the best experts on this subject based on the ideXlab platform.
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achieving high energy density in pvdf based polymer blends suppression of early polarization saturation and enhancement of breakdown strength
ACS Applied Materials & Interfaces, 2016Co-Authors: Xin Zhang, Yang Shen, Longqing Chen, Zhonghui Shen, Jianyong Jiang, Cewen NanAbstract:Polymers with high dielectric strength and favorable flexibility have been considered promising materials for Dielectrics and energy storage applications, while the achievable energy density (Ue) of polymer is rather limited by the intrinsic low dielectric constant and ferroelectric hysteresis. Polyvinylidene fluoride-trifluoroethylene-chlorofluoroethylene (P(VDF-TrFE-CFE)) with ultrahigh er of >50 is considered promising in achieving high Ue of polymer Dielectrics. However, P(VDF-TrFE-CFE) only exhibits moderate Ue due to the early saturation of electrical polarization at low electric field. In this contribution, we show that, by blending P(VDF-TrFE-CFE) with polyvinylidene fluoride (PVDF), the early saturation of P(VDF-TrFE-CFE) is substantially suppressed, giving rise to concomitant enhancement of dielectric permittivity and breakdown strength. An ultrahigh energy density of 19.6 J/cm3 is thus achieved at ∼640 kV/mm, which is 1600% greater than Ue of the benchmark biaxially oriented polypropylene (BOPP...
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sandwich structured polymer nanocomposites with high energy density and great charge discharge efficiency at elevated temperatures
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Feihua Liu, Matthew R. Gadinski, Guangzu Zhang, Tiannan Yang, Longqing Chen, Qing WangAbstract:Abstract 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.
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modulation of topological structure induces ultrahigh energy density of graphene ba0 6sr0 4tio3 nanofiber polymer nanocomposites
Nano Energy, 2015Co-Authors: Yang Shen, Longqing Chen, Xin Zhang, Weiwei Chen, Jianjun Wang, Yuhan Guan, Yuanhua Lin, Cewen NanAbstract:Abstract Dielectric capacitors have been the major enabler for a number of applications in advanced electronic and electrical power systems due to their capability of ultrafast charging–discharging and ultrahigh power density. High energy density Dielectrics are highly desirable in order to reduce the size and cost of dielectric capacitors, which is critical for electrical pulse-power systems and power electronics in electric vehicles. Polymer nanocomposites are promising in raising the low energy density of neat polymer Dielectrics of current use. In this study, a class of sandwich-structured nanocomposites are prepared by a facile hot-pressing method. Polyvinylidene fluoride nanomcomposite layers filled with graphene oxide nanosheets coated with TiO2 nanoparticles (G-layers) or Ba0.6Sr0.4TiO3 nanofibers (B-layers) are cast from solution and assembled into sandwich-structured nanocomposites with reversed topological strcuture (BGB & GBG). An ultrahigh energy density of ~14.6 J/cm3 is achieved in the BGB nanocomposites. Phase-field simulations reveal the significant implications of topological structure on the dielectric performance of the nanocomposites. By rational design of topological structure and the dielectric property of the individual layers, favorable distribution of local electrical field could be achieved among the constituent layers of the sandwich-structured nanocomposites, giving rise to the concomitant enhancement of electrical polarization and dielectric breakdown strength, and hence ultrahigh energy density.
Cewen Nan - One of the best experts on this subject based on the ideXlab platform.
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achieving high energy density in pvdf based polymer blends suppression of early polarization saturation and enhancement of breakdown strength
ACS Applied Materials & Interfaces, 2016Co-Authors: Xin Zhang, Yang Shen, Longqing Chen, Zhonghui Shen, Jianyong Jiang, Cewen NanAbstract:Polymers with high dielectric strength and favorable flexibility have been considered promising materials for Dielectrics and energy storage applications, while the achievable energy density (Ue) of polymer is rather limited by the intrinsic low dielectric constant and ferroelectric hysteresis. Polyvinylidene fluoride-trifluoroethylene-chlorofluoroethylene (P(VDF-TrFE-CFE)) with ultrahigh er of >50 is considered promising in achieving high Ue of polymer Dielectrics. However, P(VDF-TrFE-CFE) only exhibits moderate Ue due to the early saturation of electrical polarization at low electric field. In this contribution, we show that, by blending P(VDF-TrFE-CFE) with polyvinylidene fluoride (PVDF), the early saturation of P(VDF-TrFE-CFE) is substantially suppressed, giving rise to concomitant enhancement of dielectric permittivity and breakdown strength. An ultrahigh energy density of 19.6 J/cm3 is thus achieved at ∼640 kV/mm, which is 1600% greater than Ue of the benchmark biaxially oriented polypropylene (BOPP...
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modulation of topological structure induces ultrahigh energy density of graphene ba0 6sr0 4tio3 nanofiber polymer nanocomposites
Nano Energy, 2015Co-Authors: Yang Shen, Longqing Chen, Xin Zhang, Weiwei Chen, Jianjun Wang, Yuhan Guan, Yuanhua Lin, Cewen NanAbstract:Abstract Dielectric capacitors have been the major enabler for a number of applications in advanced electronic and electrical power systems due to their capability of ultrafast charging–discharging and ultrahigh power density. High energy density Dielectrics are highly desirable in order to reduce the size and cost of dielectric capacitors, which is critical for electrical pulse-power systems and power electronics in electric vehicles. Polymer nanocomposites are promising in raising the low energy density of neat polymer Dielectrics of current use. In this study, a class of sandwich-structured nanocomposites are prepared by a facile hot-pressing method. Polyvinylidene fluoride nanomcomposite layers filled with graphene oxide nanosheets coated with TiO2 nanoparticles (G-layers) or Ba0.6Sr0.4TiO3 nanofibers (B-layers) are cast from solution and assembled into sandwich-structured nanocomposites with reversed topological strcuture (BGB & GBG). An ultrahigh energy density of ~14.6 J/cm3 is achieved in the BGB nanocomposites. Phase-field simulations reveal the significant implications of topological structure on the dielectric performance of the nanocomposites. By rational design of topological structure and the dielectric property of the individual layers, favorable distribution of local electrical field could be achieved among the constituent layers of the sandwich-structured nanocomposites, giving rise to the concomitant enhancement of electrical polarization and dielectric breakdown strength, and hence ultrahigh energy density.
