Resistive switching properties of layered graphene oxides (GOs) filled polymer nanocomposites (PNCs) have received tremendous attention in the field of memory devices. Herein, we report highly stable write-once-read-many-times (WORM) resistive switching properties of exfoliated GOs embedded poly(methyl methacrylate) (PMMA) thin films. The WORM characteristics of the PNC devices have been studied by varying the active layer thickness and the content of GO nanofillers. A disrupted carbon network of GOs enables defect states that act as an energy barrier for carriers and the charge transport through the PNC devices is blocked at a lower electric field. At an elevated electric field, GO sheets embedded PMMA offers percolation pathways for electron transfer, thereby making the composites electrically more conductive. The set voltage (VSET) decreases with a decrease in the active layer thickness, whereas VSET increases with a decrease in the GOs content within PNC devices. For a fixed compliance current (∼1 μA), highest ION/IOFF ratio ∼104 at 1.87 V has been achieved for the PNCs device spin-coated at 9000 rpm with 0.1 wt. % GOs content. The stability of the devices has been confirmed through retention test up to 104 s. In addition, the J-V curves are fitted and an appropriate conduction mechanism is proposed.

Functionalized layered nanohybrid materials have been thoroughly explored in numerous practical applications including photocatalysis, supercapacitors, and sensors, and have inherent potential to excel in the field of organic resistive random access memory devices as well. Herein, we report an efficient, facile, and cost-effective in situ synthesis route to prepare a layered nanohybrid by grafting cadmium sulfide (CdS) nanorods with exfoliated graphene oxide (GOs) sheets via the one-step hydrothermal functionalization technique. Such a nanohybrid material displays advantageous characteristics possessed by them due to the formation of organic–inorganic heterojunctions at their interface. Sandwiched devices, with a configuration of ITO/reduced graphene oxide–CdS/poly-methyl methacrylate (PMMA)/Al, are fabricated by dispersing different wt. % of the layered nanohybrid in a poly-methyl methacrylate (PMMA) matrix. Detailed current density vs voltage (J–V) studies exhibit excellent bipolar resistive switching characteristics reaching a very low set voltage of ∼−0.48V, high current ION/IOFF ratios of ∼106, and ultralow set/reset power densities of ∼10−8/10−6W/cm2 for devices containing 0.4 wt. % nanohybrid nanofillers. Partial reduction of GOs and the formation of heterojunctions during the synthesis process undoubtedly boost the resistive memory performances resulting from the synergistic effect in layered nanohybrid materials. The fabricated devices have been subjected to various analyses in order to test their stability, repeatability, and reliability, all of which have been found to display encouraging results.

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Organic−inorganic hybrid composites (HCs) comprising functionalized 2D materials have been given exceptional importance and have been actively employed as memory materials toward development of next-generation resistive memory devices. Herein, we use in situ functionalized rGO−ZnO HC nanofillers for the first time and report the improved memory performances such as a very low operating voltage and a high current ON/OFF ratio along with good repeatability. Hybrid polymer nanocomposite (HPNC) devices were fabricated by dispersing hydrothermally synthesized rGO−ZnO HCs in PMMA that surpass most organic resistive memory and are comparable to inorganic resistive memory in terms of device performances. The memory characteristics of the HPNCs have been modulated and optimized by varying the proportion of hybrid nanofillers. Highly stable and repeatable memory phenomena have been observed for all the devices and the switching voltages were modulated systematically. Very low switching voltages in the range of ∼−0.60 to −0.74 V and high current I ON /I OFF ratio of ≈ 10 6 have been obtained for the device with the loading of 0.5 wt % hybrid nanofillers. The carrier transport mechanism through the devices have been elucidated with the help of a suitable energy band diagram. Our study implies that HPNC materials are excellent candidates for organic memory application and provide useful information about the underlying carrier transport mechanism associated with resistive switching phenomena.

A facile chemical method of acid treatment has been followed for the cutting of graphene oxides sheet to extract graphene oxide quantum dots (GOQDs) in aqueous medium at different pH. Strong blue emission and excitation dependent photoluminescence (PL) spectrum are observed in GOQDs. Relative PL quantum yield is measured as high as ∼30% for the GOQDs synthesized at pH11. Presence of defect related states and oxygen containing functional groups in GOQDs are confirmed through Raman and Fourier transform infrared analysis, respectively. High resolution transmission electron microscopy analysis suggests that the sizes of GOQDs are distributed in the range ∼2.0-8.0 nm with d-spacing of 0.245 nm. AFM measurement confirms the topography height of GOQDs in the range ∼6.0-9.0 nm. Synthesized GOQDs at different pH are dispersed in poly (vinyl alcohol) (PVA) matrix and spin coated to fabricate polymer nanocomposites (PNCs) devices. Electrical studies have been performed which display writeonce-read-many characteristics and the set voltage (V SET ) increases with the increase in pH of the GOQDs. Very low V SET ∼−0.9 V and / I I ON OFF ∼10 4 have been obtained for the device containing GOQDs synthesized at pH1. Retention tests up to 10 4 s are performed for the PNCs devices in order to confirm the stability. A suitable energy band diagram is proposed to discuss the carrier transport through the composites devices.