Kunshan Hisense Electronics Co.

Kunshan, China

Kunshan Hisense Electronics Co.

Kunshan, China

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Hou Y.,East China University of Science and Technology | Lu Z.,East China University of Science and Technology | Lu Z.,CAS Shanghai Institute of Technical Physics | Pu T.,East China University of Science and Technology | And 4 more authors.
Applied Physics Letters | Year: 2013

The polarization switching and imprint behaviors with different pulse and unipolar poling processes for ferroelectric poly(vinylidene fluoride- trifluoroethylene) (P(VDF-TrFE)) copolymer ultrathin films have been studied. Compared with results for samples only through the certain protocol we studied previously, the much faster switching speed and lower voltage shift are observed for films with certain protocol as well as certain unipolar poling. The analyses show that these properties are strongly dependent on the directions of the switching and unipolar poling field. The results provide another effective route to design the optimum protocol for ferroelectric random access memory based on P(VDF-TrFE) copolymer ultrathin film. © 2013 AIP Publishing LLC.


Lu Z.,East China University of Science and Technology | Lu Z.,Beijing Jiaotong University | Deng Z.,Beijing Jiaotong University | Hou Y.,East China University of Science and Technology | And 2 more authors.
Thin Solid Films | Year: 2012

The similarities and differences of alkali metal chlorides (sodium chloride (NaCl), potassium chloride (KCl), rubidium chloride (RbCl) and cesium chloride (CsCl)) applied in organic light-emitting diodes (OLEDs) are investigated. The behavior is similar for the OLEDs with these four chlorides as electron injection layer (EIL). Their maximum luminance and efficiency at 100 mA/cm 2 are within the ranges of 18 550 ± 600 (cd/m2) with an error of 3.23% and 4.09 ± 0.15 (cd/A) within an error of 3.67%, respectively. The similar performance is due to almost identical electron injection barrier for NaCl, KCl, RbCl and CsCl as EIL. Interestingly, the properties are different for devices with chlorides inserted inside tris (8-hydroxyquinoline) aluminum at the position of 20 nm away from aluminum cathode, labeled as NaCl-, KCl-, RbCl- and CsCl- devices. The relation of luminance is CsCl- > RbCl- = KCl- > NaCl-, where > and = mean better than and the same as, respectively. And the device efficiencies are decreased from CsCl to NaCl. That is, the sort order of the efficiencies is CsCl- > RbCl- > KCl- > NaCl-. The mechanism is explained by tunneling model in terms of various energy gaps estimated by optical electronegativity of NaCl, KCl, RbCl and CsCl. © 2012 Elsevier B.V.


Zhang X.,Shanghai University of Engineering Science | Zhang X.,East China University of Science and Technology | Du X.,Shanghai University of Engineering Science | Hou Y.,East China University of Science and Technology | And 3 more authors.
Applied Physics Letters | Year: 2014

The temperature dependence of imprint in ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer thin film capacitors has been investigated. The descriptions of imprint versus different temperatures and annealing process are given. It is found that the temperature-induced shift of the imprint rate is limited for all the investigated temperature conditions, and this low shift is mainly associated with the competition between the trap states increasing and detrapping process induced by the temperature rise. Also, the annealing temperature-dependent imprint rates in the polymer chains hzave been analyzed, and the annealed cell shows low imprint rate after 104 switches at an annealing temperature above 100 C. Re-annealing recovery process of "inherent" imprint in the ferroelectric thin film capacitor shows improved imprint behaviors, which may be a wake-up of the polarization and detrapping from imprint traps. The internal electric fields for these processes are well analyzed and it is thought that the effective fields as well as charge trap states in ferroelectric layers are strongly responsible for the switching behaviors. This result may be useful for memory device design if extended to cover the temperature dependence of the polarization reversal based on P(VDF-TrFE) copolymer thin film. © 2014 AIP Publishing LLC.


Xu H.S.,East China University of Science and Technology | Zhang Y.N.,East China University of Science and Technology | Zhang X.L.,East China University of Science and Technology | Zhang X.L.,Shanghai University of Engineering Science | Ma Y.P.,Kunshan Hisense Electronics Co.
Ferroelectrics | Year: 2011

A functional interlayer, poly(3,4-ethylene dioxythioohene)-poly(styrene sulfonic) acid, is introduced as a buffer layer between the metal electrodes of a capacitor composed of ferroelectric poly(vinylidene fluoridetrifluoroethylene) copolymer ultrathin film. The sandwiched structure shows prominent ferroelectric properties even as the thickness of P(VDF-TrFE) film is reduced to 50 nm and the fatigue property is also improved tremendously. We demonstrate that the proton in the PSSH instead of the electron in the PEDOT plays a significant role to improve the ferroelectric properties of P(VDFTrFE), furthermore, polyvinyl phosphoric acid as well as other polyacid also supplies the proton. © Taylor & Francis Group, LLC.


Zhang X.,East China University of Science and Technology | Zhang X.,Shanghai University of Engineering Science | Xu H.,East China University of Science and Technology | Xu H.,Kunshan Hisense Electronics Co. | Zhang Y.,East China University of Science and Technology
Journal of Physics D: Applied Physics | Year: 2011

The experimental intrinsic coercive field of ferroelectric poly(vinylidene fluoride-trifluoethylene) copolymer films, with both bottom and top gold electrodes is measured at a wide temperature range. In the lower temperature region from -20 to 25 °C, the temperature dependence of coercive field shows good agreement with the prediction by the Landau-Ginzburg (LG) mean-field theory. In the higher temperature region from 25 to 80 °C, the coercive field shows a slow decrease with the increased temperature, where the LG theory is not applicable any more. The temperature-dependent changes in the polymer chains have been analysed. A reversible 'inherent fatigue' is observed from the partially recovered remanent polarization after re-annealing a fatigued P(VDF-TrFE) film. FTIR spectra indicate that the interchain spacing does not change from 10 to 107 switching cycles while the degree of all-trans ferroelectric phase decreases gradually with applied switching cycles. After a re-annealing treatment, ferroelectric phase recovers and dipoles at the boundary of crystallites acquire much higher energy. © 2011 IOP Publishing Ltd.


Lu Z.,East China University of Science and Technology | Hou Y.,East China University of Science and Technology | Xiao J.,Taishan University | Xu H.,East China University of Science and Technology | Xu H.,Kunshan Hisense Electronics Co.
Vacuum | Year: 2014

Based on the device structure of indium tin oxide (ITO)/N,N′- diphenyl-N,N′-bis(1-naphthyl-phenyl)-1,1′-biphenyl-4, 4′-diamine (NPB)/4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7- tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB)/tris (8-hydroxy quinoline) aluminum (Alq3)/NPB/bathocuproine (BCP)/Al, the variation of emissive spectra with voltage and emissive unit (DCJTB/Alq3/NPB) parameters has been investigated. All electroluminescent spectra contain two components: blue emission from NPB and red emission of DCJTB. The Alq3 emission is not observed due to its relative shallow LUMO (the lowest unoccupied molecular orbital) and deep HOMO (the highest occupied molecular orbital). The emission of NPB is increased with voltages as well as the thickness of NPB and Alq3 for more holes escape from DCJTB and get in NPB to recombine with electrons. © 2014 Elsevier Ltd. All rights reserved.


Hou Y.,East China University of Science and Technology | Zhang X.,East China University of Science and Technology | Zhang Y.,East China University of Science and Technology | Xu G.,Kunshan Hisense Electronics Co. | Xu H.,East China University of Science and Technology
Journal of Applied Physics | Year: 2012

A universal model and experiments on the polarization switching for ferroelectric poly(vinylidene fluoride-trifluoroethylene) copolymer ultra-thin films with an interface layer have been studied. It is found that polarization switching could complete if the capacitance of the interface layer is large enough compared with that of the ferroelectric film. Based on this model, a conducting polymer, poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonic) acid, is introduced as an interface layer between metal electrodes and ferroelectric polymer film and the switching property measurements well agree with the simulation results of the model. These findings provide an effective route to enhance the polarization switching for the ferroelectric films, which is promising for potential applications. © 2012 American Institute of Physics.


Hou Y.,East China University of Science and Technology | Zhang X.,East China University of Science and Technology | Zhang Y.,East China University of Science and Technology | Xu G.,Kunshan Hisense Electronics Co. | Xu H.,East China University of Science and Technology
Journal of Applied Physics | Year: 2012

The high-temperature ferroelectric behaviors for poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer ultrathin films with electroactive interlayers have been studied. The different electroactive polymers, commercial poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonic) acid (PEDOT-PSSH), in situ synthesized PEDOT-PSSH with high PEDOT ratio and poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonic) ammonia (PEDOT-PSSNH 4), are used as the interlayer between P(VDF-TrFE) and metal electrodes. It is found that the ferroelectric properties at high temperature are strongly dependent on the interlayer and the faster degradation occurs on the sample with the interlayer which has enough protons as compensating charges. Further analysis on the polarization response behaviors and capacitance shows that the high-temperature ferroelectric properties are more closely associated with the compensating charges in interlayer than the ferroelectric film itself, illustrating the importance of the appropriate interlayer materials. © 2012 American Institute of Physics.


Hou Y.,East China University of Science and Technology | Lu Z.,East China University of Science and Technology | Pu T.,East China University of Science and Technology | Zhang Y.,East China University of Science and Technology | And 2 more authors.
Applied Physics Letters | Year: 2013

The polarization switching behaviors with different pulse processes for ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer ultrathin films have been studied. The faster switching speed with imprint time is observed for the films with the certain switching and imprint directions. The internal electric fields for these processes are well analyzed, and it is found that the effective fields as well as charge trap states in ferroelectric layers are strongly responsible for the switching behaviors. This result provides an effective route to design the optimum protocol for ferroelectric random access memory based on P(VDF-TrFE) copolymer ultrathin film. © 2013 American Institute of Physics.


Hou Y.,East China University of Science and Technology | Lu Z.,East China University of Science and Technology | Zhang Y.,East China University of Science and Technology | Xu G.,Kunshan Hisense Electronics Co. | Xu H.,East China University of Science and Technology
Applied Physics Letters | Year: 2012

The imprint behaviors for poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer ultrathin films with electroactive interlayers have been studied. The different electroactive polymers are used as the interlayer between P(VDF-TrFE) and metal electrodes. It is found that the smaller voltage shift is observed for the samples with electroactive interlayers and the imprint properties are improved substantially after the electroactive interlayers are introduced. The charge trap accumulation in P(VDF-TrFE) films without and with interlayers is analyzed and it is thought that the traps would be partially compensated by the free charges from the electroactive interlayers, illustrating the importance of the appropriate interlayer materials. © 2012 American Institute of Physics.

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