New random copolymers with pendant carbazole donor and 1,3,4-oxadiazole acceptor for high performance memory device applications

Fang, Yi‐Kai; Liu, Cheng‐Liang; Chen, Wen‐Chang

doi:10.1039/c0jm02535f

Cited by 80 publications

(73 citation statements)

References 48 publications

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“…[1][2][3][4][5][6][7] The active layer exhibits distinct high and low conductance responses to applied voltages for application as digital memory devices with simple sandwiched structures. The reported polymer-based systems for such applications included conjugated polymers, [8][9][10] functional polyimides (PIs), [11][12][13] polymers with pendent electroactive chromophores, [14][15][16] and polymeric composites.…”

Section: Introductionmentioning

confidence: 99%

Tunable electrical memory characteristics by the morphology of self-assembled block copolymers:PCBM nanocomposite films

et al. 2012

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Resistive switchable memory devices were fabricated using self-assembled composite thin films of asymmetric poly(styrene-block-4-vinylpyridine) (PS-b-P4VP) block copolymers (BCP) and fullerene derivatives (PCBM). L1 (with a longer PS block) was comprised of discrete vertical P4VP nanocylinders embedded within the PS matrix whereas L2 (with a longer P4VP block) revealed a reverse morphology with a horizontal orientation. They were used to control the spatial location or distribution of the PCBM and the resultant memory characteristics. The devices with ITO/BCP:PCBM/ Al configurations exhibited variable multi-electronic characteristics, changing from insulating to bistable memory switching and highly conducting, as the PCBM content increased. The L1:PCBM memory device showed non-volatile write-once-read-many-times (WORM) memory behavior but the L2:PCBM device exhibited a volatile nature of static random access memory (SRAM). Both L1 and L2: PCBM composite devices revealed the improved switching performance upon solvent annealing procedures of the composite thin film. Our results suggested that the controlled morphology of the BCP/PCBM composite could create nanoscale charge-storage elements for a high density memory device with a reduced bit cell size.

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Section: Introductionmentioning

confidence: 99%

Tunable electrical memory characteristics by the morphology of self-assembled block copolymers:PCBM nanocomposite films

et al. 2012

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“…The incorporated electron-accepting OXD moieties could serve as the hole-blocking layer in the active memory layer. 28 Under a low electrical field, the trapped charge carriers will induce a charged layer in the polymer film near the electrodes and prevent further charge injection from the electrodes. Under a high electric field with sufficient energy to overcome the charge-trapping barrier, intramolecular CTs can occur between the electron donor and acceptor.…”

Section: Resultsmentioning

confidence: 99%

“…The improved device performance over poly(9,9-dioctylfluorene) is due to the better electron injection and transport in PF-OXD, and the efficient energy transfer from the OXD side chain to the PF main chains. By using electron-donating 9-(4-vinylphenyl)carbazole and electron-accepting 2-phenyl-5-(4-vinylphenyl)-1,3,4-oxadiazole or 2-(4-vinylbiphenyl)-5-(4-phenyl)-1,3, 4-oxadiazole as side chains, Chen and colleagues 28 prepared a nonconjugated random copolymer by the nitroxidemediated free-radical polymerization method. Both experimental and theoretical results indicated that the CT between the pendant donor and acceptor was relatively weak without significant orbital hybridization.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and memory performance of a conjugated polymer with an integrated fluorene, carbazole and oxadiazole backbone

Zeng

Liu

Zhang

et al. 2011

Polym J

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A new soluble conjugated polymer, poly[{9-(4-methoxyphenyl)-9H-carbazole}(9,9-dioctylfluorene)(2,5-diphenyl-1,3,4-oxadiazole)] (PCFO), was synthesized through the Suzuki coupling reaction. The absolute fluorescence quantum yield of PCFO was measured using the integrating sphere of a photoluminescence spectrofluorometer, and changed from 49.1% for a dilute tetrahydrofuran solution to 16.2% for a thin film due to the existence of a strong fluorescence quenching effect in the solid state. The HOMO-LUMO bandgap (3.07 eV) calculated from the electrochemical measurement is nearly identical to the optical bandgap (3.06 eV) estimated from the ultraviolet/visible absorption onset data. This film was attached to aluminum and indium-tin oxide contacts to fabricate a memory device with typical bistable electrical switching, nonvolatile write-once read-many-times memory performance, a turn-on voltage of BÀ2.3 V and an ON/OFF ratio of B10 5 . Degradation of the current density was observed for neither the ON nor OFF states after one hundred million continuous read cycles, which indicates that both states were insensitive to read cycles. Keywords: donor-acceptor system; molecular devices; polymer memory; synthesis INTRODUCTIONPolymer memories are proposed to revolutionize electrical applications by providing extremely inexpensive, lightweight and transparent modules that can be fabricated onto plastic, glass or the top layer of CMOS hybrid integration circuits, 1,2 and have been identified as an emerging memory technology by the International Technology Roadmap for Semiconductors since year 2005. 3 Rather than encoding '0'and '1' as a charge stored in the cell of a silicon device, polymer memory stores data in an entirely different form, such as in a highand low-conductivity response to an applied voltage. 4 The molecular structure of polymers can be tailored by functionalizing them with electron donors (D) and acceptors (A) of different strengths, spacer moieties of different steric effects for the electroactive pendant groups, or nanostructured electroactive materials, to induce different memory behaviors in simple metal/polymer/metal devices. 5,6 Very recently, Liu and Chen 7 highlighted the recent developments in D-A polymers for resistive switching memory device applications including conjugated polymers, functional polyimides, nonconjugated pendent polymers and polymer composites. D/A polymer materials (usually carbazole or

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“…We have explored the electrical memory characteristics of non-conjugated random copolymers containing pendent electrondonating 9-(4-vinylphenyl)carbazole (VPK) or 4-vinyltriphenylamine (VTPA), and electron-accepting 2-phenyl-5-(4-vinylphenyl)-1,3,4-oxadiazole (OXD) or 2-(4-vinylbiphenyl)-5-(4-phenyl)-1,3,4-oxadiazole (BOXD). The electrical switching behavior of such random copolymers could be tuned through the donor/acceptor ratio or characteristics of pendant groups [39,40]. Also, we discovered the wellcorrelation of the electrical memory characteristics with the pendant conjugated chain length in polystyrene derivatives with electron-donating oligofluorene pendant moieties [41].…”

Section: Introductionmentioning

confidence: 97%

“…We are particularly interested in the development of the polymers with pendantconjugated moieties for resistive-type memory device applications [38][39][40][41]. For examples, polymers with pendant carbazole-containing groups exhibited holetransporting ability that dominated the conduction.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, properties, and electrical memory characteristics of new diblock copolymers of polystyrene-block-poly(styrene-pyrene)

Lin

Lee

et al. 2011

Polym. Bull.

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In this study, we report the synthesis, properties, and electrical memory characteristics of new diblock copolymers, polystyrene-block-poly(styrene-pyrene) (PS-b-P(St-Py)), prepared by combining atom transfer radical polymerization and Suzuki coupling reaction. The effects of the St-Py block chain length on the electronic energy level, photophysical properties, and memory characteristics were explored. The PS 42 -b-P(St-Py) 108 and PS 66 -b-P(St-Py) 67 devices exhibited a dynamic random access memory characteristics with different turn-on threshold voltages of -2.7 and -3.1 V, respectively. Moreover, these memory devices showed a high ON/OFF current ratio of 10 9 and were electrically stable for at least 10 4 s in both ON and OFF states. However, the PS 113 -b-P(St-Py) 45 -based device displayed an insulating state in a low current variation of 10 -12 to 10 -14 A, which had a short St-Py block length. The mechanism of the switching behavior was explained by the charge hopping conduction between the pyrene units with coexisting charge-trapping environment. The volatility of the memory effect was depended on the ability of charge trapping/back transferring of trapped charge. Electronic supplementary material The online version of this article (The present study suggested that the electrical memory characteristics could be efficiently tuned through the block ratio between insulating segment and pendantconjugated segment of the diblock polymers.

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New random copolymers with pendant carbazole donor and 1,3,4-oxadiazole acceptor for high performance memory device applications

Cited by 80 publications

References 48 publications

Tunable electrical memory characteristics by the morphology of self-assembled block copolymers:PCBM nanocomposite films

Tunable electrical memory characteristics by the morphology of self-assembled block copolymers:PCBM nanocomposite films

Synthesis and memory performance of a conjugated polymer with an integrated fluorene, carbazole and oxadiazole backbone

Synthesis, properties, and electrical memory characteristics of new diblock copolymers of polystyrene-block-poly(styrene-pyrene)

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