RESUMEN
In this work, the effects of graphene oxide (GO) concentrations (1.5 wt.%, 2.5 wt.%, and 5 wt.%) on the structural, morphological, optical, and luminescence properties of zinc oxide nanorods (ZnO NRs)/GO nanocomposites, synthesized by a facile hydrothermal process, were investigated. X-ray diffraction (XRD) patterns of NRs revealed the hexagonal wurtzite structure for all composites with an average coherence length of about 40-60 nm. A scanning electron microscopy (SEM) study confirmed the presence of transparent and wrinkled, dense GO nanosheets among flower-like ZnO nanorods, depending on the GO amounts used in preparation. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) absorption spectroscopy, and photoluminescence (PL) measurements revealed the impact of GO concentration on the optical and luminescence properties of ZnO NRs/GO nanocomposites. The energy band gap of the ZnO nanorods was independent of GO concentration. Photoluminescence spectra of nanocomposites showed a significant decrease in the intensities in the visible light range and red shifted suggesting a charge transfer process. The nanocomposites' chromaticity coordinates for CIE 1931 color space were estimated to be (0.33, 0.34), close to pure white ones. The obtained results highlight the possibility of using these nanocomposites to achieve good performance and suitability for optoelectronic applications.
RESUMEN
The electrical conduction mechanisms were investigated for the CdS and Cu-doped CdS (CdS:Cu) nanoparticles embedded in polyvinyl alcohol (PVA) (PVA/CdS and PVA/CdS:Cu) nanocomposites; synthesized by the chemical Sol Gel method on indium tin-oxide (ITO) substrate. X-ray diffraction pattern results show that the PVA/CdS nanocomposite is hawleyite-sturcture and PVA/CdS:Cu nanocomposites show greenockite-hawelyite mixed structure. The sizes of CdS and CdS:Cu nanoparticles were estimated from transmission electron microscopy (TEM) images and are ≈4 nm and ≈10 nm respectively; which were formed inside the PVA polymer layer. The devices were fabricated with Ag and ITO as electrodes with PVA/CdS and PVA/CdS:Cu nanocomposites as an active layers. The current-voltage (I-V ) relationships measurements shows the nature is extended memrisitve features for both PVA/CdS and PVA/CdS:Cu nanocomposites. The ION/IOFF ratios are enhanced and become more prominent in case of PVA/CdS:Cu nanocomposites device. The resistive switching characteristic show Schottky, Trapped-charge limited current (TCLC) and Space charge limited conduction (SCLC) mechanisms in Ag/PVA/CdS/ITO device; whereas Schottky, Ohmic, TCLC and SCLC were observed in Ag/PVA/CdS:Cu/ITO device.