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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.

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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.

We use charge modulation spectroscopy (CMS) in model holes-only devices to address the reason for decreasing quantum efficiency with increasing drive current in organic light-emitting diodes based on Alq3 doped with the red dye DCJTB. We are able to measure the density of DCJTB+ and correlate it with the diminution of the photoluminescence. The magnitude and DCJTB+ density dependence of the photoluminescence reduction are roughly consistent with quenching of the singlet-excited-state of DCJTB via Förster energy transfer to DCJTB+. At low DCJTB+ densities, the quenching is stronger than theory would predict and we propose that singlet energy transport among DCJTB molecules extends the distance over which quenching by DCJTB+ is effective. Since the Förster mechanism can be responsible for charge-induced PL quenching as large as 70% even though DCJTB+ is very weakly absorbing where DCJTB singlets fluoresce, it may be difficult to avoid quenching by electrically generated species.