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Ferroelectric Poly (ferroelectric + poly)

Distribution by Scientific Domains

Polymers and Materials Science	100%

Selected Abstracts

Non-volatile Ferroelectric Poly(vinylidene fluoride- co -trifluoroethylene) Memory Based on a Single-Crystalline Tri-isopropylsilylethynyl Pentacene Field-Effect Transistor

ADVANCED FUNCTIONAL MATERIALS, Issue 10 2009
Seok Ju Kang
Abstract A new type of nonvolatile ferroelectric poly(vinylidene fluoride- co -trifluoroethylene) (P(VDF-TrFE)) memory based on an organic thin-film transistor (OTFT) with a single crystal of tri-isopropylsilylethynyl pentacene (TIPS-PEN) as the active layer is developed. A bottom-gate OTFT is fabricated with a thin P(VDF-TrFE) film gate insulator on which a one-dimensional ribbon-type TIPS-PEN single crystal, grown via a solvent-exchange method, is positioned between the Au source and drain electrodes. Post-thermal treatment optimizes the interface between the flat, single-crystalline ab plane of TIPS-PEN and the polycrystalline P(VDF-TrFE) surface with characteristic needle-like crystalline lamellae. As a consequence, the memory device exhibits a substantially stable source,drain current modulation with an ON/OFF ratio hysteresis greater than 103, which is superior to a ferroelectric P(VDF-TrFE) OTFT that has a vacuum-evaporated pentacene layer. Data retention longer than 5,×,104 s is additionally achieved in ambient conditions by incorporating an interlayer between the gate electrode and P(VDF-TrFE) thin film. The device is environmentally stable for more than 40 days without additional passivation. The deposition of a seed solution of TIPS-PEN on the chemically micropatterned surface allows fabrication arrays of TIPS-PEN single crystals that can be potentially useful for integrated arrays of ferroelectric polymeric TFT memory. [source]

Fully Transparent Non-volatile Memory Thin-Film Transistors Using an Organic Ferroelectric and Oxide Semiconductor Below 200,°C

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2010
Sung-Min Yoon
Abstract A fully transparent non-volatile memory thin-film transistor (T-MTFT) is demonstrated. The gate stack is composed of organic ferroelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] and oxide semiconducting Al-Zn-Sn-O (AZTO) layers, in which thin Al2O3 is introduced between two layers. All the fabrication processes are performed below 200,°C on the glass substrate. The transmittance of the fabricated device was more than 90% at the wavelength of 550,nm. The memory window obtained in the T-MTFT was 7.5,V with a gate voltage sweep of ,10 to 10,V, and it was still 1.8,V even with a lower voltage sweep of ,6 to 6,V. The field-effect mobility, subthreshold swing, on/off ratio, and gate leakage currents were obtained to be 32.2,cm2 V,1 s,1, 0.45,V decade,1, 108, and 10,13 A, respectively. All these characteristics correspond to the best performances among all types of non-volatile memory transistors reported so far, although the programming speed and retention time should be more improved. [source]

Printable Ferroelectric PVDF/PMMA Blend Films with Ultralow Roughness for Low Voltage Non-Volatile Polymer Memory

ADVANCED FUNCTIONAL MATERIALS, Issue 17 2009
Seok Ju Kang
Abstract Here, a facile route to fabricate thin ferroelectric poly(vinylidene fluoride) (PVDF)/poly(methylmethacrylate) (PMMA) blend films with very low surface roughness based on spin-coating and subsequent melt-quenching is described. Amorphous PMMA in a blend film effectively retards the rapid crystallization of PVDF upon quenching, giving rise to a thin and flat ferroelectric film with nanometer scale , -type PVDF crystals. The still, flat interfaces of the blend film with metal electrode and/or an organic semi-conducting channel layer enable fabrication of a highly reliable ferroelectric capacitor and transistor memory unit operating at voltages as low as 15,V. For instance, with a TIPS-pentacene single crystal as an active semi-conducting layer, a flexible ferroelectric field effect transistor shows a clockwise I,V hysteresis with a drain current bistability of 103 and data retention time of more than 15,h at ±15,V gate voltage. Furthermore, the robust interfacial homogeneity of the ferroelectric film is highly beneficial for transfer printing in which arrays of metal/ferroelectric/metal micro-capacitors are developed over a large area with well defined edge sharpness. [source]

Non-volatile Ferroelectric Poly(vinylidene fluoride- co -trifluoroethylene) Memory Based on a Single-Crystalline Tri-isopropylsilylethynyl Pentacene Field-Effect Transistor

Electrocaloric Materials for Solid-State Refrigeration

ADVANCED MATERIALS, Issue 19 2009
Sheng-Guo Lu
Abstract The electrocaloric effect (ECE) in dielectric materials has great potential in realizing solid-state cooling devices with compact size and high efficiency, which are highly desirable for a broad range of applications. This paper presents the general considerations for dielectric materials to achieve large ECE and reviews the experimental efforts investigating ECE in various polar dielectrics. For practical cooling devices, an ECE material must possess a large isothermal entropy change besides a large adiabatic temperature change. We show that polar dielectrics operated at temperatures near order,disorder transition have potential to achieve large ECE due to the possibility of large change in polarization induced by electric field and large entropy change associated with the polarization change. We further show that indeed the ferroelectric poly(vinylidene fluoride,trifluoroethylene)-based polymers display a large ECE, i.e., an isothermal entropy change of more than 55,J,(kgK),1 and an adiabatic temperature change of more than 12,°C, at temperatures above the order,disorder transition. [source]