• Korean Journal of Optics and Photonics
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• v.12 no.3
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• pp.225-229
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• 2001

Relaxation phenomena of the electro-optic coefficient in ferroelectric copolymer P (VDF- TrFE) were studied. The electro-optic coefficient of copolymers was measured by simple reflection method and the decay curves were fitted by KWW stretched exponentials. The copolymers poled near Tc. Were shown to be more stable than the copolymer poled at lower temperatures. Further, the relaxation time t depending on temperature was found to follow Arrhenius behavior and it was found that the activation energy of 50/50 mol% P (VDF-TrFE) copolymer is larger than that of 72/28 mol% copolymer. As a result, the ferroelectric copolymer with VDF of 50 mol% is was more stable.stable.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.125-125
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• 2009

유기물 강유전체 재료를 이용한 비휘발성 메모리에 대한 연구가 활발하게 진행되고 있다. 현재까지 알려진 대표적인 재료는 P(VDF-TrFE)이다. P(VDF-TrFE)는 결정화 온도가 낮기 때문에 저온공정이 가능하여 향 후 플렉서블 소자 응용에도 유망하다. 최근의 연구결과에서는 고유전율의 절연층을 삽입함으로써 누설전류를 감소시켜, 저전압에서 우수한 강유전성이 얻어질이 보고되고 있다. 본 논문에서는 P(VDF-TrFE)의 조성 변화를 통하여 최적의 강유전성이 얻어지는 조건을 찾고자 노력하였으며, 조성 변화에 따른 구조적, 전기적 특성에 대하여 보고한다.

• Journal of the Korean Vacuum Society
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• v.17 no.3
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• pp.220-225
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• 2008

In this research, the P(VDF-TrFE) copolymer thin films were prepared by the physical vapor deposition and studied to their piezoelectric properties. In the case of a specimen produced by varying the deposition temperature from $260^{\circ}C$ to $300^{\circ}C$, its piezoelectric coefficient($d_{33}$) increased from 32.3pC/N to 36.28pC/N, and piezoelectric voltage coefficient($g_{33}$) from $793{\times}10^{-3}V{\cdot}m/N$ to $910.5{\times}10^{-3}V{\cdot}m/N$. On the basis of these experimental results, we concluded that the P(VDF-TrFE) copolymer thin film prepared at $300^{\circ}C$ showed the optimum piezoelectric properties. At the deposition temperature of $320^{\circ}C$, its piezoelectric coefficient(d33) decreased 25.3 pC/N and piezoelectric voltage coefficient($g_{33}$) $680{\times}10^{-3}V{\cdot}m/N$.

• Fibers and Polymers
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• v.4 no.4
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• pp.188-194
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• 2003

Phase behavior and spinodal phase separation kinetics in binary blends of a random copolymer of vinylidene fluoride and trifluoroethylene (75/25) [P(VDF/TrFE)] and poly(l,4-butylene adipate) (PBA) have been investigated by means of optical microscopic observation and time-resolved light scattering. The blends exhibited a typical lower critical solution temperature (LCST)∼${34}^{\circ}C$ above the melting temperature of the P(VDF/TrFE) crystals over the entire blend composition range. P(VDF/TrFE) and PBA were totally miscible in the temperature gap between the melting point of P(VDF/TrFE) and the LCST. Temperature jump experiments of the 3/7 P(VDF/TrFE)/PBA blend were carried out on a light-scattering apparatus from a single-phase melt state (${180}^{\circ}C$) to a two-phase region (205∼${215}^{\circ}C$). Since the late stage of spinodal decomposition (SD) is prevalent in the 3/7 blend, SD was analyzed using a power law scheme. Self-similarity was preserved well in the late stage of SD in the 3/7 blend.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.367-370
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• 2000

In this study, thin films of 70/30 and 80/20 mol% P(VDF-TrFE) copolymers were fabricated by physical vapor deposition method. In order to determine the optimum deposition condition, the copolymer thin films were fabricated in the heating temperature of 260$^{\circ}C$, 280$^{\circ}C$, and 300$^{\circ}C$. The deposition rate was measured in a real time by thickness monitor. The surface image of prepared thin films was analyzed by using AFM. From the results of TG-DTA,70/30 and 80/20 mol% P(VDF-TrFE) copolymers were observed the Curie transition point below the melting point. As the results of AFM and FT-IR analysis, we determined that the optimum deposition temperature was 300$^{\circ}C$.

• Korean Journal of Materials Research
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• v.19 no.4
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• pp.228-231
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• 2009

Phase transition in ferroelectric polymer is very interesting behavior and has been widely studied for real device applications, such as actuators and sensors. Through the phase transition, there is structural change resulting in the change of electrical and optical properties. In this study, we fabricated the Febry-Perot interferometer with the thin film of ferroelectric P(VDF-TrFE) 50/50 mol% copolymer, and thermo-optical properties were investigated. The effective thermo-optical coefficient of P(VDF-TrFE) was obtained as $2.3{\sim}3.8{\times}10^{-4}/K$ in the ferroelectric temperature region ($45^{\circ}C{\sim}65^{\circ}C$) and $6.0{\times}10^{-4}/K$ in the phase transition temperature region ($65^{\circ}C{\sim}85^{\circ}C$), which is a larger than optical silica-fiber and PMMA. The resonance transmission peak of P(VDF-TrFE) with the variation of temperature showed hysteretic variation and the phase transition temperature of the polymer in heating condition was higher than in the cooling condition. The elimination of the hysteretic phase transition of P(VDF-TrFE) is necessary for practical applications of optical devices.

• Polymer(Korea)
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• v.35 no.5
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• pp.375-377
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• 2011

$PbTiO_3$/P(VDF/TrFE) 0~3 composites thin films with 0.10 and 0.13 of ceramic volume fraction factor have been fabricated by two-step spin coating technique and analyzed. 0~3 connectivity of $PbTiO_3$/P(VDF/TrFE) composites film was observed successfully by SEM micrography. The SEM picture confirmed 0~3 connectivity. And, in all the properties, 0~3 $PbTiO_3$/P(VDF/TrFE) composites film was superior to P(VDF/TrFE) copolymer. Therefore, with a good low-dielectric constant and a high pyroelectric coefficient, the composite thin films can be used for a new pyroelectric infrared sensor of higher performance.

• Journal of Electrochemical Science and Technology
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• v.9 no.2
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• pp.126-132
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• 2018

For the first time, an innovative approach using P(VDF-TrFE) as a polymer electrolyte for high efficiency, all-solid-state supercapacitors is presented. The polymer electrolyte was successfully achieved by dissolving P(VDF-TrFE) copolymers in dimethylformamide (DMF). Thermal analysis and infrared spectroscopy revealed excellent thermal stability up to $400^{\circ}C$ and copolymer's interaction with DMF. Electrochemical capacitors fabricated using P(VDF-TrFE) in DMF and ZnO NWs demonstrated high capacitive performance. Furthermore, the gel electrolyte-based supercapacitors demonstrated excellent mechanical durability up to a bend angle of $120^{\circ}$. Novel P(VDF-TrFE) electrolytes could be a promising approach for applications in flexible, fabric-based, and high-efficiency energy devices.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.1
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• pp.1-5
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• 2001

P(VDF/TrFE) copolymer thin films with 70/30 and 80/20 mol% VDF (polyvinylidene fluoride) and TrFE (trifluoroethylene) rates were prepared by using a vapor deposition method, During thin films were prepared, the substrate temperatures were maintained at 30 $^{\circ}C$ and 120 $^{\circ}C$, and the heating source temperature was fixed at 350 $^{\circ}C$. Contary to PVDF homopolymer, P(VDF/TrFE) copolymers showed the Curie point(Tc) below the melting point. The Curie point (Tc) and the melting point of the P(VDF/TrFE) copolymers were changed as a function of substrate temperature and the VDF mol%. The Curie point and the melting point of P(VDF/TreFE) thin films decreased and increased with increasing substrate temperature, respectively. Also with increasing VDF mol%, the melting point decreased slightly, however the Curie point increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.85-86
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• 2007

A poly(vinylidene fluoride-trifluoroethyene) (P(VDF-TrFE)) copolymer thin film having ${\beta}$ phase was prepared by sol-gel method. The electrical properties of the film were studied to evaluate the possibility for appling to a ferroelectric random access memory. In order to characterize its electrical properties, we produced a MFS (metal-ferroelectric-semiconductor) structure by evaporation of Au electrodes. The C-V (capacitance-voltage) measurement revealed that the Au/P(VDF-TrFE)/Si structure with a 4 wt% film had a memory window width of about 0.5V for a bias voltage sweep of 1V.