New Fullerene-Based Polymers and Their Electrical Memory Characteristics

Chemically Controlled Volatile and Nonvolatile Resistive Memory Characteristics of Novel Oxygen-Based Polymers

Recent advancements in modern microelectronics continuously increase the data storage capacity of modern devices, but they require delicate and costly fabrication processes. As alternatives to conventional inorganic based semiconductors, semiconducting polymers are of academic and industrial interest for their cost-efficiency, power efficiency, and flexible processability. Here, we have synthesized a series of novel oxygen-based polymers through the postmodification reactions of poly(ethylene-alt-maleate) with various oxybenzyl alcohol derivatives. The oxygen-based polymers are thermally stable up to 180 °C, and their nanoscale film devices exhibit reliable, power efficient p-type unipolar volatile and nonvolatile resistive memory characteristics with high ON/OFF current ratios. Additionally, when given a higher number of oxygen atoms in oxyphenyl side groups, the thin film polymer devices demonstrate a wide operational film thickness range. The memory characteristics depend on the oxyphenyl moieties functioning as charge trap sites, where a combination of Schottky emission and trap-limited space charge limited conductions in OFF-state and hopping conduction in ON-state are observed. This study demonstrates the chemical incorporation of oxyphenyl derivatives into polymer dielectrics as a powerful development tool for p-type resistive memory materials.

Ambipolar polyimides with pendant groups based on 9H-thioxanthene-9-one derivatives: synthesis, thermostability, electrochemical and electrochromic properties

New thermally stable polyimides with pendant groups based on 9H-thioxanthene-9-one and its S,S-dioxide display electrochemical and electrochromic activities caused by radical anion states of pendant groups and in-chain imide moieties.

Interfacial synthesis of a large-area coordination polymer membrane for rewritable nonvolatile memory devices

The facile synthesis of large-area coordination polymer membranes with controlled nanoscale thicknesses is critical towards their applications in information storage electronics. Here, we have reported a facile and substrate-independent interfacial synthesis method for preparing a large-area two-dimensional (2D) coordination polymer membrane at the air–liquid interface. The prepared high-quality 2D membrane could be transferred onto an indium tin oxide (ITO) substrate to construct a nonvolatile memory device, which showed reversible switching with a high ON/OFF current ratio of 10³, good stability and a long retention time. Our discovery of resistive switching with nonvolatile bistability based on the substrate-independent growth of the 2D coordination polymer membrane holds significant promise for the development of solution-processable nonvolatile memory devices with a miniaturized device size.

Stable nonvolatile memory devices with a high ON/OFF current ratio have been realized based on a large-area two-dimensional coordination polymer membrane.

Structural and electronic properties of a CN fullerene with N = 20, 60, 80, 180, and 240

In this paper, the structural and electronic properties of a C_N fullerene with N = 20, 60, 80, 180, and 240 have been investigated using a sp³ tight-binding model. The analytical expressions for the calculation of the total number of carbon atoms, hexagons, pentagons, and bonds found within the geometrical structure of a C_N fullerene have been developed and verified using the simulation, therefore proving the validation of both the simulation and analytical results. The simulation results show that the total number of carbon atoms within fullerene is equal to the value of N and the total number of hexagons, pentagons, and bonds within the structure of a fullerene increases with the increase in the value of N. Further, the electronic properties of these fullerenes have been identified with the help of their energy level diagrams obtained using the simulation. It has been observed that the C₂₀ and C₈₀ fullerenes are metallic because of their zero band gaps while the C₆₀ fullerene is an insulator with a very wide band gap of 5 eV whereas the C₁₈₀ and C₂₄₀ fullerenes are semiconducting with band gaps of 1.43 eV and 1.05 eV, respectively. Finally, it has been observed from these studies that the metallic fullerenes are best suited for interconnects and the semiconducting fullerenes are bested suited as a channel material for designing high-performance nanoelectronic devices.

Evaluating technological emergence using text analytics: two case technologies and three approaches

Scientometric methods have long been used to identify technological trajectories, but we have seldom seen reproducible methods that allow for the identification of a technological emergence in a set of documents. This study evaluates the use of three different reproducible approaches for identifying the emergence of technological novelties in scientific publications. The selected approaches are term counting technique, the emergence score (EScore) and Latent Dirichlet Allocation (LDA). We found that the methods provide somewhat distinct perspectives on technological. The term count based method identifies detailed emergence patterns. EScore is a complex bibliometric indicator that provides a holistic view of emergence by considering several parameters, namely term frequency, size, and origin of the research community. LDA traces emergence at the thematic level and provides insights on the linkages between emerging research topics. The results suggest that term counting produces results practical for operational purposes, while LDA offers insight at a strategic level.

Theoretical identification of seven C80 fullerene isomers by XPS and NEXAFS spectroscopy

The molecular geometries and C1s NEXAFS spectra of seven IPR-satisfying isomers of fullerene C₈₀.

Synthesis of new conjugated polymers with coordinated praseodymium complexes for polymer memory devices

A series of novel praseodymium(Pr)-coordinated polymers with phthalimide moieties were synthesized. The effects of the phthalimide moiety and neutral Pr complex on the polymer memory device performance were investigated.

Synthesis and Preliminary Characterization of a PPE-Type Polymer Containing Substituted Fullerenes and Transition Metal Ligation Sites

A substituted fullerene was incorporated into a PPE-conjugated polymer repeat unit. This subunit was then polymerized via Sonogashira coupling with other repeat units to create polymeric systems approaching 50 repeat units (based on GPC characterization). Bipyridine ligands were incorporated into some of these repeat units to provide sites for transition metal coordination. Photophysical characterization of the absorption and emission properties of these systems shows excited states located on both the fullerene and aromatic backbone of the polymers that exist in a thermally controlled equilibrium. Future work will explore other substituted polyaromatic systems using similar methodologies.