Tunable Memristic Characteristics Based on Graphene Oxide Charge-Trap Memory

Two-dimensional material-based memristive devices for alternative computing

Two-dimensional (2D) materials have emerged as promising building blocks for next generation memristive devices, owing to their unique electronic, mechanical, and thermal properties, resulting in effective switching mechanisms for charge transport. Memristors are key components in a wide range of applications including neuromorphic computing, which is becoming increasingly important in artificial intelligence applications. Crossbar arrays are an important component in the development of hardware-based neural networks composed of 2D materials. In this paper, we summarize the current state of research on 2D material-based memristive devices utilizing different switching mechanisms, along with the application of these devices in neuromorphic crossbar arrays. Additionally, we discuss the challenges and future directions for the field.

Optical and UV Shielding Properties of Inorganic Nanoparticles Embedded in Polymethyl Methacrylate Nanocomposite Freestanding Films

Polymethyl methacrylate (PMMA) is an interesting polymer employed in various applications due to its outstanding properties. However, its electrical and mechanical properties can be further improved by incorporating nanoparticles, and in particular, PMMA nanocomposite with nanoparticles provides various multifunctional properties. This work reports PMMA nanocomposite preparation and structural and optical characterizations incorporating carbon nanotubes (CNTs), TiO2 nanoparticles, and carbon quantum dots (CQDs). CNT/PMMA, TiO2/PMMA, and CQD/PMMA nanocomposite freestanding films were prepared using a simple solution method. Various properties of the prepared composite films were analyzed using scanning electron microscopy, X-ray diffraction, photoluminescence, Fourier transform infrared, and UV-Vis and Raman spectroscopy. Optical parameters and photocatalytic dye degradation for the films are reported, focusing on the properties of the materials. The CNT/PMMA, TiO2/PMMA, and CQD/PMMA films achieved, respectively, good electrical conductivity, photodegradation, and fluorescence compared with other composite films.

Controlled Memristic Behavior of Metal-Organic Framework as a Promising Memory Device

Metal-organic frameworks (MOFs) have attracted considerable interests for sensing, electrochemical, and catalytic applications. Most significantly, MOFs with highly accessible sites on their surface have promising potential for applications in high-performance computing architecture. In this paper, Mg-MOF-74 (a MOF built of Mg(II) ions linked by 2,5-dioxido-1,4-benzenedicarboxylate (DOBDC) ligands) and graphene oxide composites (Mg-MOF-74@GO) were first used as an active layer to fabricate ternary memory devices. A comprehensive investigation of the multi-bit data storage performance for Mg-MOF-74@GO composites was discussed and summarized. Moreover, the structure change of Mg-MOF-74@GO after introducing GO was thoroughly studied. The as-fabricated resistive random access memory (RRAM) devices exhibit a ternary memristic behavior with low SET voltage, an RHRS/RIRS/RLRS ratio of 103:102:1, superior retention (>104 s), and reliability performance (>102 cycles). Herein, Mg-MOF-74@GO composite films in constructing memory devices were presented with GO-mediated ternary memristic properties, where the distinct resistance states were controlled to achieve multi-bit data storage. The hydrogen bonding system and defects of GO adsorbed in Mg-MOF-74 are the reason for the ternary memristic behavior. The charge trapping assisted hopping is proposed as the operation mechanism, which is further confirmed by XRD and Raman spectra. The GO-mediated Mg-MOF-74 memory device exhibits potential applications in ultrahigh-density information storage systems and in-memory computing paradigms.

Spectroscopic Studies of Styrylquinoline Copolymers with Different Substituents

The aim of the study was to present the influence of various styrylquinoline (StQ) substituents on the luminescence, structural, and optical properties of StQ-containing copolymers. StQ-containing copolymers were synthesized by free-radical thermoinitiated polymerization. The calculations of the copolymerization ratios for the obtained copolymers were based on the basis of the integrated peak areas of the ¹H NMR spectra in CDCl₃. The luminescence measurements show that the change in the nature of the electron-donating and electron-withdrawing of the substituent shifts the emission band to longer wavelengths and causes a transition from blue fluorescence to green or yellow and orange (or even white), regardless of the electronic nature of the introduced substituent group. The structural properties were measured by Fourier-Transform Infrared (FTIR) and Raman spectroscopies. For all of the compounds, we observed similarities in the bands in FTIR and Raman measurements. The optical parameters were obtained from the absorbance measurements. Additionally, Scanning Electron Microscopy (SEM) was used to study the surface topography of the thin layers on the glass substrate. The SEM images confirm that we obtained smoother layers for two copolymers. The computational Density Functional Theory (DFT) analysis fully supports the beneficial features of the analyzed systems for their applications in optoelectronic devices. Based on the obtained results, it can be concluded that all of the studied styrylquinolines are promising materials for applications in organic light-emitting diodes (OLEDs). However, COP1 with an OCH₃ donor substituent possess a wider luminescence band, and its layer is smoother and more transparent.

Decade of 2D-materials-based RRAM devices: a review

Two dimensional (2D) materials have offered unique electrical, chemical, mechanical and physical properties over the past decade owing to their ultrathin, flexible, and multilayer structure. These layered materials are being used in numerous electronic devices for various applications, and this review will specifically focus on the resistive random access memories (RRAMs) based on 2D materials and their nanocomposites. This study presents the device structures, conduction mechanisms, resistive switching properties, fabrication technologies, challenges and future aspects of 2D-materials-based RRAMs. Graphene, derivatives of graphene and MoS2 have been the major contributors among 2D materials for the application of RRAMs; however, other members of this family such as hBN, MoSe2, WS2 and WSe2 have also been inspected more recently as the functional materials of nonvolatile RRAM devices. Conduction in these devices is usually dominated by either the penetration of metallic ions or migration of intrinsic species. Most prominent advantages offered by RRAM devices based on 2D materials include fast switching speed (<10 ns), less power losses (10 pJ), lower threshold voltage (<1 V) long retention time (>10 years), high electrical endurance (>108 voltage cycles) and extended mechanical robustness (500 bending cycles). Resistive switching properties of 2D materials have been further enhanced by blending them with metallic nanoparticles, organic polymers and inorganic semiconductors in various forms.

Development of Bioelectronic Devices Using Bionanohybrid Materials for Biocomputation System

Bioelectronic devices have been researched widely because of their potential applications, such as information storage devices, biosensors, diagnosis systems, organism-mimicking processing system cell chips, and neural-mimicking systems. Introducing biomolecules including proteins, DNA, and RNA on silicon-based substrates has shown the powerful potential for granting various functional properties to chips, including specific functional electronic properties. Until now, to extend and improve their properties and performance, organic and inorganic materials such as graphene and gold nanoparticles have been combined with biomolecules. In particular, bionanohybrid materials that are composed of biomolecules and other materials have been researched because they can perform core roles of information storage and signal processing in bioelectronic devices using the unique properties derived from biomolecules. This review discusses bioelectronic devices related to computation systems such as biomemory, biologic gates, and bioprocessors based on bionanohybrid materials with a selective overview of recent research. This review contains a new direction for the development of bioelectronic devices to develop biocomputation systems using biomolecules in the future.