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This work reports on the fabrication of ZnO polymer-based hybrid ultraviolet (UV) photodiodes with a configuration of ITO/ZnO-nanorod/F8BT/PEDOT:PSS/Ag. The diode was fabricated by spin-coating p-type F8BT and PEDOT:PSS polymers on hydrothermally grown n-type ZnO nanorods. The growth of ZnO nanorods was carried out by varying seed layer alcohols, viz., methanol, ethanol, isopropanol, and aqueous ethanol (70% alcohol). These solvents influenced the nanorod diameter, surface coverage, and surface defects. Herein, we demonstrate that the uniformity and defects in ZnO nanorods govern the electrical properties, photoresponse, and figures of merit of the photodiodes. In particular, the photodiodes are evaluated on their rectification ratio, ideality factor (η), responsivity (R), external quantum efficiency (EQE), and response time (Tdecay). The photodiode fabricated with ZnO nanorods grown on the methanol seeding layer has demonstrated the best performance, owing to the uniform surface coverage of the nanorods. It also presented the highest rectification ratio of ∼640, a Tdecay of 108 s, a η of 2, an EQE of ∼2760%, and an R of ∼8.14 A/W at −2 V.

Light-emitting diodes (LED) are widely employed in display applications and lighting systems. Further research on LED that incorporates carbon nanostructures and metal nanoparticles exhibiting surface plasmon resonance has demonstrated a significant improvement in device performance. These devices offer lower turn-on voltages, higher external quantum efficiencies, and luminance. De facto, plasmonic nanoparticles, such as Au and Ag have boosted the luminance of red, green, and blue emissions. When combined with carbon nanostructures they additionally offer new possibilities towards lightweight and flexible devices with better thermal management. This review surveys the diverse possibilities to combine various inorganic, organic, and carbon nanostructures along with plasmonic nanoparticles. Such combinations would allow an enhancement in the overall properties of LED.

ZnO is an effective photocatalyst applied to the degradation of organic dyes in aqueous media. In this study, the UV-light and sunlight-driven photocatalytic activities of ZnO nanoparticles are evaluated. A handheld Lovibond photometer was purposefully calibrated in order to monitor the dye removal in outdoor conditions. The effect of ZnO defect states, i.e., the presence of zinc and oxygen defects on the photocatalytic activity was probed for two types of dyes: fuchsin and methylene blue. Three morphologies of ZnO nanoparticles were deliberately selected, i.e., spherical, facetted and a mix of spherical and facetted, ascertained via transmission electron microscopy. Aqueous and non-aqueous sol-gel routes were applied to their synthesis in order to tailor their size, morphology and defect states. Raman spectroscopy demonstrated that the spherical nanoparticles contained a high amount of oxygen vacancies and zinc interstitials. Photoluminescence spectroscopy revealed that the facetted nanoparticles harbored zinc vacancies in addition to oxygen vacancies. A mechanism for dye degradation based on the possible surface defects in facetted nanoparticles is proposed in this work. The reusability of these nanoparticles for five cycles of dye degradation was also analyzed. More specifically, facetted ZnO nanoparticles tend to exhibit higher efficiencies and reusability than spherical nanoparticles.

We report on the synthesis of ZnO nanoparticles and their hybrids consisting of carbon nanotubes (CNT) and polystyrene sulfonate (PEDOT:PSS). A non-aqueous sol–gel route along with hydrated and anhydrous acetate precursors were selected for their syntheses. Transmission electron microscopy (TEM) studies revealed their spherical shape with an average size of 5 nm. TEM also confirmed the successful synthesis of ZnO-CNT and ZnO-PEDOT:PSS hybrid nanocomposites. In fact, the choice of precursors has a direct influence on the chemical and optical properties of the ZnO-based nanomaterials. The ZnO nanoparticles prepared with anhydrous acetate precursor contained a high amount of oxygen vacancies, which tend to degrade the polymer macromolecule, as confirmed from X-ray photoelectron spectroscopy and Raman spectroscopy. Furthermore, a relative increase in hydroxyl functional groups in the ZnO-CNT samples was observed. These functional groups were instrumental in the successful decoration of CNT and in producing the defect-related photoluminescence emission in ZnO-CNT.

In this work, we report on the anomalous conductance induced by hydrogen (H2) gas on as-grown and gold/palladium (Au/Pd)-catalyzed zinc oxide nanoflowers (ZnO NFs). The catalyzed ZnO NFs exhibited a sharp increase in conductivity on H2 exposure and the conductance persisted for several hours on removing H2. This anomalous behavior is in sharp contrast to conventional ZnO-based H2 gas sensors wherein the conductivity decreases on removing H2 gas. The as-grown ZnO NF sample showed drastic response to H2 under UV illumination with its conductivity increasing by almost 500%. We attribute our observation to catalyzed chemidesorption of oxygen from the ZnO lattice. [ABSTRACT FROM AUTHOR]