Structure and electrical properties of Ag-ultrafine-particle–polymer thin films

Gao, Hongjun; Xue, Zheng; Wu, Qi; Pang, Shengyang

doi:10.1116/1.588244

Cited by 15 publications

(6 citation statements)

References 3 publications

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“…[5][6][7][8][9]19 Under proper experimental conditions, 9 good thin films which are single crystals of the organic material can be formed. However, under other conditions, 6,7 the deposited material forms nonuniform, dendritic aggregates with the unusual "seahorse" morphology.…”

Section: Ionized Cluster Beam Deposition Methodsmentioning

confidence: 99%

Unique Dendritic Patterns in Organic Thin Films

et al. 1998

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We present the formation of unique and striking dendritic "seahorse" patterns in the growth of fullerene-tetracyanoquinodimethane (C 60 -TCNQ) or pure TCNQ thin films. The films were fabricated by an ionized-cluster-beam deposition method. Energetic neutral and charged clusters were deposited on amorphous carbon substrates. Transmission electron microscopy reveals that the elemental pattern is a "seahorse" -that is, an S-shaped form, with "fins" on the outer edges of the curved arms forming the S. Such forms possess an approximate symmetry under rotations by π, but strongly break two-dimensional inversion symmetry. A novel formation mechanism is proposed, involving the aggregation of neutral and charged clusters, such that some electrostatic charge is trapped on each growing island. This charge gives rise to a longrange field which biases the growth in a nontrivial way. The broken symmetry arises from the strong amplification of noise in the diffusive aggregation process by the effects of the electrostatic field -that is, the symmetry breaking is spontaneous. This picture is tested by applying a transverse electric field during growth: for sufficiently strong fields, the S-shaped "seahorses" lose their curvature, while retaining the feature of having two main arms. These results demonstrate the importance of electrostatic effects in the growth process, and are consistent with the growth mechanism described here. 337 Fractals 1998.06:337-350. Downloaded from www.worldscientific.com by YALE UNIVERSITY on 05/15/15. For personal use only. Fractals 1998.06:337-350. Downloaded from www.worldscientific.com by YALE UNIVERSITY on 05/15/15. For personal use only.

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Section: Ionized Cluster Beam Deposition Methodsmentioning

confidence: 99%

Unique Dendritic Patterns in Organic Thin Films

et al. 1998

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“…[72,74] Conjugated polymers have been used as the hosts, namely poly(3-hexylthiophene) containing Au-dodecanethiol [75] or carbon nanotubes. [76] Nominally uncoated Ag particles have been imbedded in polymer matrices by using ionized cluster beams, [77] by simple thermal co-evaporation, [78] and by plasma polymerization of hexamethyldisilazane or benzene. [79] In the last case, there was sufficient control over the composition to create a range of volume fractions of metallic NPs, resulting in films that were respectively dielectric, percolating, or metallic.…”

Section: Reviewmentioning

confidence: 99%

Nonvolatile Memory Elements Based on Organic Materials

2007

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Many organic electronic devices exhibit switching behavior, and have therefore been proposed as the basis for a nonvolatile memory (NVM) technology. This Review summarizes the materials that have been used in switching devices, and describes the variety of device behavior observed in their charge–voltage (capacitive) or current–voltage (resistive) response. A critical summary of the proposed charge‐transport mechanisms for resistive switching is given, focusing particularly on the role of filamentary conduction and of deliberately introduced or accidental nanoparticles. The reported device parameters (on–off ratio, on‐state current, switching time, retention time, cycling endurance, and rectification) are compared with those that would be necessary for a viable memory technology.

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“…Polymers containing aromatic amine or fluorene moieties have been investigated as hole-transporting materials for organic light emitting diodes (OLEDs) as well as p-type semiconductors for organic field effect transistors (OFETs) and organic solar cells. − These p-type polymers have recently been employed in memory devices that exhibit volatile and nonvolatile memory characteristics. − In contrast, organic molecules bearing cyano groups have been used as electron acceptors (i.e., n-type materials) in memory devices. − Therefore, it is interesting to mold these p- and n-type organic components into a single fully π-conjugated polymer system with the aim of enhancing and controlling device performance by adjusting the highest occupied and lowest unoccupied molecular orbital (HOMO and LUMO) levels and the band gap. Recently, the synthesis of such a π-conjugated aromatic amine and fluorene polymer was successfully demonstrated with Pd-catalyzed amination polymerization .…”

Section: Introductionmentioning

confidence: 99%

Digital Memory Versatility of Fully π-Conjugated Donor–Acceptor Hybrid Polymers

Kim

et al. 2014

ACS Appl. Mater. Interfaces

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The fully π-conjugated donor-acceptor hybrid polymers Fl-TPA, Fl-TPA-TCNE, and Fl-TPA-TCNQ, which are composed of fluorene (Fl), triphenylamine (TPA), dimethylphenylamine, alkyne, alkyne-tetracyanoethylene (TCNE) adduct, and alkyne-7,7,8,8-tetracyanoquinodimethane (TCNQ) adduct, were synthesized. These polymers are completely amorphous in the solid film state and thermally stable up to 291-409 °C. Their molecular orbital levels and band gaps vary with their compositions. The TCNE and TCNQ units, despite their electron-acceptor characteristics, were found to enhance the π-conjugation lengths of Fl-TPA-TCNE and Fl-TPA-TCNQ (i.e., to produce red shifts in their absorption spectra and significant reductions in their band gaps). These changes are reflected in the electrical digital memory behavior of the polymers. Moreover, the TCNE and TCNQ units were found to diversify the digital memory modes and to widen the active polymer layer thickness window. In devices with aluminum top and bottom electrodes, the Fl-TPA polymer exhibits stable unipolar permanent memory behavior with high reliability. The Fl-TPA-TCNE and Fl-TPA-TCNQ devices exhibit stable unipolar permanent memory behavior as well as dynamic random access memory behavior with excellent reliability. These polymer devices were found to operate by either hole injection or hole injection along with electron injection, depending on the polymer composition. Overall, this study demonstrated that the incorporation of π-conjugated cyano moieties, which control both the π-conjugation length and electron-accepting power, is a sound approach for the design and synthesis of high-performance digital memory polymers. The TCNE and TCNQ polymers synthesized in this study are highly suitable active materials for the low-cost mass production of high-performance, polarity-free, programmable, volatile, and permanent memory devices that can be operated with very low power consumption, high ON/OFF current ratios, and high reliability.

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Structure and electrical properties of Ag-ultrafine-particle–polymer thin films

Cited by 15 publications

References 3 publications

Unique Dendritic Patterns in Organic Thin Films

Unique Dendritic Patterns in Organic Thin Films

Nonvolatile Memory Elements Based on Organic Materials

Digital Memory Versatility of Fully π-Conjugated Donor–Acceptor Hybrid Polymers

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