We report ZnO nanorod-graphene hybrid architectures (ZnO-G HAs) composed of regular arrays of ZnO nanorods formed on few-layer graphene films transferred to transparent and/or flexible substrates. The ZnO-G HAs exhibited a high current flow reaching ∼1.1 mA at an applied bias of 1 V and good optical transmittance in the range of 70-80%, comparable to those of a graphene layer. In addition, cathodoluminescence images and photoluminescence spectra of the ZnO-G HAs showed distinct light emission involving optical transitions in the ZnO nanorod array. Moreover, a bending test demonstrated that the ZnO-G HAs exhibit excellent mechanical flexibility and structural stability for the bending radius down to ∼4 mm. Our results suggest that the 1D-2D HAs provide unique and multiple functions as can be applicable for next-generation electronic and optoelectronic systems.

The effects on the photovoltaic performance of the incorporation of SnO2 nanoparticles into the polymer of a solid-state dye-sensitized solar cell (DSC) based on the poly(ethylene oxide)/poly(ethylene glycol) dimethyl ether solid electrolyte are studied in this paper. It has been found that the addition of SnO2 nanoparticles to the solid electrolyte produces several key changes in the properties of the solid-state DSC that produced a better performance of the device. Therefore, we have measured an improvement in electrolyte conductivity by a factor of 2, a linear rise in the TiO2 conduction band position, a reduction in the electron recombination rate, and a decrease in charge-transfer resistance at the counterlectrode/electrolyte interface. All these improvements produced an increase in the power conversion efficiency from 4.5 to 5.3% at 1 sun condition, a consequence of the increase of both V oc (oc = open circuit) and J sc (sc = short circuit) without any sacrifice in FF (fill factor). The origin of these changes has been associated to the strong Lewis acidic character of SnO2 nanoparticles yielding to the formation of a I3 – percolation layer for holes at the surface of SnO2 and the reduction of the concentration of free I3 – and K+ ions inside the pores of TiO2. From these results, it is concluded that the physicochemical effects of inorganic nanofiller in the polymer electrolyte may also be considered a good route in designing the high efficiency solid-state DSCs employing the polymer electrolyte.

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We report the catalyst-free synthesis of ZnO nanobranches on Si nanowires using metalorganic chemical vapor deposition. The formation of single-crystalline ZnO nanobranches on Si nanowire backbones has been confirmed by lattice resolved transmission electron microscopy. Depending on the growth parameters, especially the growth temperature, the morphology and size of the ZnO nanobranches evolved from nanothorn-shaped (at 350°C) to nanoneedle-shaped structures (at 500°C). When the growth temperature was further increased to 800°C, thin ZnO nanowire branches grew out of the Si nanowire backbones coated with thin ZnO shells, whereas no ZnO branch was formed on bare Si nanowires due to limited nucleation. The growth behavior was further exploited to fabricate ZnO/Si nanowire networks by growing the ZnO nanowires selectively on laterally aligned Si-ZnO core-shell nanowire arrays. In addition, cathodoluminescent properties of ZnO nanobranches on Si nanowire backbones are discussed with respect to position and size.