Polymer memory devices with widely tunable memory characteristics based on functional copolynaphthalimides bearing varied fluorene and triphenylamine moieties

Effect of a "Zn Bridge" on the Consecutively Tunable Retention Characteristics of Volatile Random Access Memory Materials

Polyimide memory materials with a donor-acceptor structure based on a charge-transfer mechanism exhibit great potential for next-generation information storage technology due to their outstanding high-temperature resistance and good dimensional and chemical stability. Precisely controlling memory performance by limited chemical decoration is one of core challenges in this field. Most reported work mainly focuses on designing novel and elaborate electron donors or acceptors for the expected memory behavior of polyimides; this takes a lot of time and is not always efficacious. Herein, we report a series of porphyrinated copolyimides coPI-Znx (x=5, 10, 20, 50, 80), where x represents the mole percentage of Zn ion in the central core of the porphyrin. Experimental and theoretical analysis indicate that the Zn ion could play a vital bridge role in promoting the formation and stabilization of a charge-transfer complex by enhancing the hybridization of local and charge transfer (HLCT) excitations of porphyrinated polyimides, endowing coPI-Znx with volatile random access memory performance and continuously tunable retention time. This work could provide one simple strategy to precisely regulate memory performance merely by altering the metal content in porphyrinated polyimides.

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.

Highly flexible and stable resistive switching devices based on WS2 nanosheets:poly(methylmethacrylate) nanocomposites

This paper reports data for the electrical characteristics and the operating mechanisms of flexible resistive switching devices based on WS₂ nanosheets (NSs) dispersed in a poly(methyl methacrylate) (PMMA) layer. The ON/OFF ratio of the memristive device based on an Al/WS₂ NSs:PMMA/indium tin oxides (ITO) structure was approximately 5.9 × 10⁴. The memristive device based on the WS₂ NSs also exhibited the bipolar switching characteristics with low power consumption and great performance in the bent state with radii of the curvatures of 20 and 10 mm. Especially, the results obtained after bending the device were similar to those observed before bending. The device showed nearly the same ON/OFF ratio for a retention time of 1 × 10⁴ sec, and the number of endurance cycles was greater than 1 × 10². The set voltage and the reset voltage probability distributions for the setting and the resetting processes indicated bipolar switching characteristics. The operating and the carrier transport mechanisms of the Al/WS₂ NSs:PMMA/ITO device could be explained based on the current-voltage results with the aid of an energy band diagram.

Flexible Memristive Devices Based on InP/ZnSe/ZnS Core-Multishell Quantum Dot Nanocomposites

The effects of the ZnS shell layer on the memory performances of flexible memristive devices based on quantum dots (QDs) with an InP/ZnSe/ZnS core-multishell structure embedded in a poly(methylmethacrylate) layer were investigated. The on/off ratios of the devices based on QDs with an InP/ZnSe core-shell structure and with an InP/ZnSe/ZnS core-multishell structure were approximately 4.2 × 10² and 8.5 × 10³, respectively, indicative of enhanced charge storage capability in the latter. After bending, the memory characteristics of the memristive devices based on QDs with the InP/ZnSe/ZnS structure were similar to those before bending. In addition, those devices maintained the same on/off ratios for retention time of 1 × 10⁴ s, and the number of endurance cycles was above 1 × 10². The reset voltages ranged from -2.3 to -3.1 V, and the set voltages ranged from 1.3 to 2.1 V, indicative of reliable electrical characteristics. Furthermore, the possible operating mechanisms of the devices are presented on the basis of the electron trapping and release mode.

Synthesis and optical and electrochemical memory properties of fluorene–triphenylamine alternating copolymer

A fluorene–triphenylamine copolymer (PF–TPA) was designed and synthesized under Suzuki coupling reaction conditions in this work. It exhibited a typical electrical conductance switching behavior and non-volatile flash memory effects.

Direct synthesis of triphenylamine-containing polyarylsulfones from commercially available aniline

A novel triphenylamine-containing polyarylsulfone (PAS-TPA) was synthesized from commercially available aniline and 1,1′-sulfonylbis(4-fluorobenzene) via two-step N–C coupling reaction under nucleophilic substitution polycondensation condition. Subsequently, a new series of polysulfones with different TPA contents (PSU-TPAs) was developed by the same method. Both PAS-TPA and PSU-TPAs not only exhibited good thermal stability and solubility but also exhibited intense ultraviolet absorption and fluorescence and high fluorescence quantum yield (approximately 16–42%). Their ideal highest occupied molecular orbital level (approximately −5.5 to −5.6) indicated the potential application of these polymers in organic photoelectronic fields.

Incorporation of SnO2 nanoparticles in PMMA for performance enhancement of a transparent organic resistive memory device

Various sizes of SnO₂ NPs have been successfully synthesized and embedded into the insulating PMMA layer sandwiched between ITO and Al electrodes.