Conventional ZnO Nanowires Research Articles

Improved flexible ZnO/CsPbBr3/Graphene UV photodetectors with interface optimization by solution process

Flexible and wearable photodetectors (PDs) that can be directly equipped on human bodies have attracted extensive attention due to their great potential in communication, health and safety applications. However, low flexibility and complicated fabrication process hinder the development of fiber- and textile-PDs for practical applications. Here, we use an efficient solution strategy to integrate CsPbBr3 nanosheets (NSs) into conventional ZnO nanowires (NWs)/graphene flexible thin film PDs based on PVDF substrate. Compared with the simpler ZnO NWs/graphene structure, the built-in electric field of ZnO/CsPbBr3 PN junction can facilitate the separation and transport of the photo-generated carriers. Moreover, the ZnO networks filled with CsPbBr3 NSs result in a smooth interface and close contacts with graphene. With the interface optimization, the enhanced transport efficiency of the carriers further leads to a high Ilight/Idark ratio of ∼103. In addition, such PVDF based PDs exhibit excellent flexibility, demonstrating great potential for practical flexible optoelectronics.

A 3-D ZnO-Nanowire Smart Photo Sensor Prepared With Through Silicon via Technology

The authors report the fabrication of a 3-D ZnO-nanowire/MOSFET smart photo sensor using through silicon via technology. It was found that the MOSFET, prepared by hot-wire chemical vapor deposition, exhibits standard saturation and pinch-off characteristics. The dynamic response of the 3-D ZnO-nanowire/MOSFET smart photo sensor was stable and reproducible with an ON–OFF current contrast ratio larger than one order of magnitude. As we turned OFF the ultraviolet illumination, it was found that the decay time was smaller than 1 s for the 3-D ZnO-nanowire/MOSFET smart photo sensor, which was significantly shorter than that observed from the conventional ZnO nanowire photo sensor.

ZnO-nanowire size effect induced ultra-high sensing response to ppb-level H2S

Presented is nano-size effect of ZnO nanowires (NWs) on sensitivity of hydrogen sulfide (H2S) detection in ambient atmosphere. The sensing mechanism of ZnO NWs for H2S detection is found coming from nano-size effect that governs both the sulfuration reaction when H2S is introduced and the following desulfuration reaction when the gas is removed from air. Based on the nano-material property of smaller dimension featuring higher chemical-activity at surface, the sensitivity of ZnO NWs to ultra-low concentration H2S is expected to be increased by shrinking the NW diameter. In our experiment, suspended micro hotplates for chemiresistive sensing are fabricated to investigate the nano-size sensing effect. Besides conventional ZnO NWs with the diameter as 50nm, a novel tree-branched nano-structure of ZnO NWs (with the branch diameter as 20nm) is in situ grown onto the sensing-area of the micro hotplate. In order to investigate the sensing effect, both the 20nm NW sensor and the 50nm NW sensor are used to experimentally detect H2S with concentrations in the range of ppb-ppm. The 20nm ZnO-NWs sensor realizes resoluble sensing to 5ppb H2S, while the 50nm sensor can only response to H2S with concentration higher than 50ppb. The well validated nano-size effect of thinner NWs featuring higher sensing response can be extended for various chemical sensing nano-materials.

A comparative study of the gas sensing properties of hierarchical ZnO nanostructures

AbstractTwo types of ZnO nanostructure have been fabricated to make a comparative study on their gas sensing performance: the conventional ZnO nanowire arrays were synthesized by hydrothermal method and the hierarchical ZnO nanowires/nanofibers nanostructures were prepared through a combination of the hydrothermal and electrospinning methods. Field emission scanning electron microscopy study showed a quiet homogeneous morphology both for both nanostructures. Three kinds of commonly used gases, such as ethanol, acetone and ammonia were chosen for ZnO nanostructure gas sensing property study. The UV‐Visible spectroscopy measurements showed a higher detection sensitivity of ZnO NWs for ammonia compared to ethanol and acetone, and an enhanced sensing performance for the hierarchical nano‐ structure, which has a higher surface to volume ratio. On the other hand, the enhancement was more obviously in the case of ethanol sensing. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Reducing recombination in ZnO photoanodes for dye sensitised solar cells through simple chemical synthesis

A method has been developed to synthesise zinc oxide nanowire arrays that demonstrate superior device performance compared to conventional ZnO nanowires within dye sensitised solar cells (DSSCs). This simple yet effective methodology has produced nanowires with triple device performance when compared to conventional ZnO nanowire DSSCs. We have fully characterised the morphology and physical properties of these wires and have demonstrated that the device improvements are due to a reduction in the recombination centres associated with the ZnO crystal.

Co-doped Y-shape ZnO nanostructures: Synthesis, structure and properties

A novel Co-doped Y-shape ZnO nanostructure was fabricated using vapor–solid process. In contrast to conventional ZnO nanowires that usually grow along c -axis, the branches of the single-crystalline Y-shaped nanostructure grew along directions that deviated significantly from the c -axis for 22 ∘,96 ∘, and 13 ∘, respectively. Transport measurement showed that the Y-shape nanostructure can function as a switch. Due to possible ordered substitution of Zn by Co, ferromagnetism was observed at 300 K and even 400 K, suggesting its potential application as an excellent dilute magnetic semiconductor nanomaterial.