Microstructured organic ferroelectric thin film capacitors by solution micromolding

Lenz, T.; Zhao, Dong; Richardson, George M.; Katsouras, Ilias; Asadi, Kamal; Glaßer, Gunnar; Zimmermann, Samuel Tobias; Stingelin, Natalie; Roelofs, W. S. Christian; Kemerink, Martijn; Blom, Paul W. M.; Leeuw, Dago M. de

doi:10.1002/pssa.201532267

Cited by 14 publications

(10 citation statements)

References 41 publications

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“…The morphology shows the characteristic needles of P(VDF‐TrFE), which are even more evident in the scanning electron microscopy (SEM) image of Figure e. We note that the same morphology is obtained for micromolded P(VDF‐TrFE) gratings . The topography before and after backfilling as derived from AFM measurements is shown in Figure f.…”

Section: Resultssupporting

confidence: 59%

“…An alternative for manipulating the phase separation is the direct patterning of the ferroelectric polymer P(VDF‐TrFE) using e‐beam lithography or nanoimprint lithography and backfilling the holes with a semiconductor. In order to arrive at well‐defined domains we used solution micromolding . The semiconducting polymer poly(9,9‐dioctylfluorene) (PFO) is patterned into linear gratings and bilinear arrays are obtained by backfilling with P(VDF‐TrFE).…”

Section: Introductionmentioning

confidence: 99%

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Downscaling and Charge Transport in Nanostructured Ferroelectric Memory Diodes Fabricated by Solution Micromolding

Lenz

Ghittorelli

Benneckendorf

et al. 2016

Adv Funct Materials

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Ferroelectric polymer memory diodes are interface devices where charge injection into the organic semiconductor is controlled by the stray electric field of the ferroelectric polymer. Key to high current density and current modulation is the areal density of well-defined interfaces. Here, bistable diodes are fabricated by using the soft lithography method solution micromolding. First, the semiconducting polymer poly(9,9-dioctylfluorene) is patterned into linear gratings. Subsequently, bilinear arrays are obtained by backfilling with the ferroelectric polymer poly(vinylidenefluoride-co-trifluoroethylene). The lateral feature size is scaled down from 2 mu m to 500 nm. Comprising memory diodes show rectifying J-V characteristics with an On-current density larger than 10(3) A m(-2) and an On/Off current ratio exceeding 10(3). The charge transport is explained by 2D numerical simulations. Since the dependence of polarization on electric field is explicitly taken into account, entire J-V characteristics can be quantitatively described. The simulations reveal that rectifying J-V characteristics are inherently related to the concave shape of the patterned ferroelectric polymer. It is argued that the exponential increase in current density with decreasing feature size can be due to confinement of the semiconductor. High On-current density combined with downscaling, rectification, and simple fabrication yield new opportunities for low-cost integration of high-density solution-processed memories

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Section: Resultssupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Downscaling and Charge Transport in Nanostructured Ferroelectric Memory Diodes Fabricated by Solution Micromolding

Lenz

Ghittorelli

Benneckendorf

et al. 2016

Adv Funct Materials

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“…The microstructure exhibits the characteristic morphology of a phase separated blend and consists of bicontinuous columnar PFO domains embedded in a P(VDF-TrFE) matrix12. The needle-like morphology is typical for semicrystalline P(VDF-TrFE)2324. The schematic cross-section of a memory diode is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Quantum tunnelling and charge accumulation in organic ferroelectric memory diodes

et al. 2017

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Non-volatile memories—providing the information storage functionality—are crucial circuit components. Solution-processed organic ferroelectric memory diodes are the non-volatile memory candidate for flexible electronics, as witnessed by the industrial demonstration of a 1 kbit reconfigurable memory fabricated on a plastic foil. Further progress, however, is limited owing to the lack of understanding of the device physics, which is required for the technological implementation of high-density arrays. Here we show that ferroelectric diodes operate as vertical field-effect transistors at the pinch-off. The tunnelling injection and charge accumulation are the fundamental mechanisms governing the device operation. Surprisingly, thermionic emission can be disregarded and the on-state current is not space charge limited. The proposed model explains and unifies a wide range of experiments, provides important design rules for the implementation of organic ferroelectric memory diodes and predicts an ultimate theoretical array density of up to 1012 bit cm−2.

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“…The absence of ferroelectric switching may be related to steric hindrance in the densely packed aggregates of BTA-OVDF or to the rough morphology that may suppress effective switching. 29 This lack of ferroelectric behavior is the more surprising, since both a BTA with alkyl sidechains and the I-ODVF itself show ferroelectricity, but the combination of both is a highly dielectric material.Ferroelectric hysteresis behavior has been found for PBI-OVDF and Pc-OVDF devices, which showed concave P-E curves, indicative of polar switching (Figures 5b,c). The coercive field (EC) and remnant polarization (Pr) for saturated polarization of PBI-OVDF and Pc-OVDF were obtained from the quasi-static ferroelectric hysteresis behavior at 50-55 o C. 30 PBI-OVDF displayed EC ~ 23 V/µm and Pr ~ 4 mC/m 2 , which are respectable values for a supramolecular organic ferroelectric.…”

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A Versatile Method for the Preparation of Ferroelectric Supramolecular Materials via Radical End-Functionalization of Vinylidene Fluoride Oligomers

et al. 2016

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ABSTRACT:A synthetic method for the end-functionalization of vinylidene fluoride oligomers (OVDF) via a radical reaction between terminal olefins and OVDF-I is described. The method shows a wide substrate scope and excellent conversions, and permits the preparation of different disc-shaped cores such as benzene-1,3,5-tricarboxamides (BTAs), perylenes bisimide (PBI) and phthalocyanines (Pc) bearing three to eight ferroelectric oligomers at their periphery. The formation, purity, OVDF conformation, and morphology of the final adducts has been assessed by a combination of techniques, such as NMR, size exclusion chromatography, (SEC), differential scanning calorimetry (DSC), polarized optical microscopy (POM) and atomic force microscopy (AFM). Finally, PBI-OVDF and Pc-OVDF materials show ferroelectric hysteresis behavior together with high remnant polarizations, with values of as high as Pr ~ 37 mC/m 2 for Pc-OVDF. This work demonstrates the potential of preparing a new set of ferroelectric materials by simply attaching OVDF oligomers to different small molecules. The use of carefully chosen small molecules paves the way to new functional materials in which ferroelectricity and electrical conductivity or light-harvesting properties coexist in a single compound. ■ INTRODUCTIONFerroelectric and piezoelectric materials play a vital role in modern technologies ranging from capacitors, hydrophones and actuators to frequency-controlled devices. 1 To further advance these technologies, access to cheaper and readily processable materials that show large ferroelectric and piezoelectric responses is highly desired. Organic materials are currently explored as they are potentially cheap, easily processable, biocompatible, and can be endowed with diverse and tunable functions. In addition, their mechanical flexibility is crucial for piezoelectric applications.Since the discovery of the first organic ferroelectric material in 1920 2 the observation of ferroelectric properties in organic materials has not been profuse. 3 In fact, most of the organic ferroelectric research is focused on polyvinylidene fluoride (PVDF). 4 PVDF displays a large remnant polarization, a short switching time, and an excellent thermal stability which makes it suitable for the fabrication of piezoelectric films. 5 The ferro-and piezoelectric properties of PVDF originate from the antiparallel intrachain arrangement of the alternated CH2 and CF2 segments in the zigzag all-anti conformation, the so-called β-form. 6 However, untreated PVDF thin films processed from the melt or from solution are not ferroelectric. 6b They possess a mixture of α, β, and γ conformations 4 and additional steps, such as mechanical stretching, 5b thermal annealing 7 and electrical poling 8 have to be performed in order to achieved the β-phase necessary to display ferro-and piezoelectric properties.More recently, vinylidene fluoride oligomers (OVDF) and poly(vinylidene fluoride-trifluoroethylene P(VDF-coTrFE), a copolymer based on PVDF, have been evaluated to enhance the format...

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Microstructured organic ferroelectric thin film capacitors by solution micromolding

Cited by 14 publications

References 41 publications

Downscaling and Charge Transport in Nanostructured Ferroelectric Memory Diodes Fabricated by Solution Micromolding

Downscaling and Charge Transport in Nanostructured Ferroelectric Memory Diodes Fabricated by Solution Micromolding

Quantum tunnelling and charge accumulation in organic ferroelectric memory diodes

A Versatile Method for the Preparation of Ferroelectric Supramolecular Materials via Radical End-Functionalization of Vinylidene Fluoride Oligomers

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