Rossana Gazia

Bio: Rossana Gazia is an academic researcher from Istituto Italiano di Tecnologia. The author has contributed to research in topics: Thin film & Pulsed laser deposition. The author has an hindex of 16, co-authored 27 publications receiving 535 citations. Previous affiliations of Rossana Gazia include University of Southampton & Instituto Politécnico Nacional.

High efficiency dye-sensitized solar cells exploiting sponge-like ZnO nanostructures.

Abstract: Sponge-like nanostructured ZnO layers were successfully employed as photoanodes for the fabrication of highly efficient dye-sensitized solar cells. The sponge-like ZnO layers were obtained by room temperature radio-frequency magnetron sputtering deposition of metallic zinc, followed by thermal oxidation treatment in an ambient atmosphere. The porous films show a 3D branched nanomorphology, with a feature similar to natural coral. The morphological and optical properties of these layers were studied through field emission scanning electron microscopy, specific surface area measurements, ultraviolet–visible transmittance and absorption spectroscopy. The sponge-like ZnO film presents a high density of branches, with a relatively high specific surface area value, and fine optical transmittance. The morphology of the porous structure provides a high number of adsorption sites for the anchoring of sensitizer molecules, making it suitable for the fabrication of ZnO-based photoanodes for dye-sensitized solar cells. The light harvesting performance of the sensitized semiconductor was evaluated by current density vs. voltage measurements, incident photon-to-electron conversion efficiency, open circuit voltage decay and impedance spectroscopy. The modelling of the electrical characteristics evidences a higher electron lifetime and a longer charge diffusion length, if compared to standard TiO2 nanoparticle based photoanodes. For ZnO films with a thickness up to 18 μm, a photoconversion efficiency as high as 6.67% and a maximum value of the incident photon-to-electron collection efficiency equal to 87% at 530 nm were demonstrated.

Triazene photopolymer dynamic release layer-assisted femtosecond laser-induced forward transfer with an active carrier substrate

Abstract: Discs of solid material have been forward transferred from thin films on transparent carrier substrates using femtosecond Ti:sapphire laser-induced forward transfer (fs-LIFT) with a triazene polymer dynamic release layer (DRL). The fluence threshold for fs-LIFT was found to be only ≈20% of the DRL ablation threshold at the laser wavelength. This decrease is attributed to ultrafast shock-wave generation in the constrained polymer layer under femtosecond irradiation being the driving force for fs-LIFT with the polymer DRL. The result is very different from the nanosecond regime, where the LIFT threshold is observed to be slightly above the polymer ablation threshold. White-light continuum generation in a carrier substrate is observed and its influence on the fs-LIFT process is discussed.

Wettability Control on ZnO Nanowires Driven by Seed Layer Properties

Abstract: This study proposes a way to control the wettability of zinc oxide nanowires (NWs) by properly selecting the kind of seed layer used to promote the growth of the wires. ZnO seed layers were synthesized on silicon and conductive substrates by a physical vapor deposition approach and a wet-chemical route, namely, the radio frequency magnetron sputtering and the spin-coating techniques, respectively. ZnO NWs were grown by a hydrothermal method on each kind of seed layer and the results were compared. The morphologies and crystallographic orientations of the seed layers and the resulting NWs were investigated with the aim of correlating the characteristics of the underlying seed layer to those of the resulting NWs. Additional insights were obtained by performing optical contact angle (OCA) measurements on ZnO seed layers to study their wettability behavior immediately after the synthesis processes and two weeks later. Hydrophilic behavior was observed in both sputtered and spin-coated fresh seed layers. After two weeks of aging, a change in the wettability and a net transition from hydrophilic to hydrophobic behavior was observed in sputtered seed layers, whereas in the spin-coated films this transition was not so pronounced and was found to be dependent on the precursor concentration. OCA measurements carried out on ZnO NWs showed that the wettability of the NWs is strictly related to the nature of the underlying seed layers and does not depend on the aging time, in contrast to the behavior of the seed layers. Depending on the deposition method, we therefore obtained either highly hydrophilic or superhydrophobic nanowires, which demonstrates the possibility to strongly control the final wetting behavior of these nanostructures for the desired application, such as self-cleaning surfaces, antireflection coatings, or substrates to anchor biofunctional agents.

Coral-shaped ZnO nanostructures for Dye Sensitized Solar Cell photoanodes

Abstract: A highly efficient ZnO photoanode for dye-sensitized solar cells was successfully grown by a simple, low cost, and scalable method. A nanostructured coral-shaped Zn layer was deposited by sputtering onto fluorine-doped tin oxide/glass slices at room temperature and then thermally oxidized in ambient atmosphere. Stoichiometry, crystalline phase, quality, and morphology of the film were investigated, evidencing the formation of a highly porous branched nanostructure, with a pure wurtzite crystalline structure. ZnO-based dye-sensitized solar cells were fabricated with customized microfluidic architecture. Dye loading on the oxide surface was analyzed with ultraviolet-visible spectroscopy, and the dependence of the cell efficiency on sensitizer incubation time and film thickness was studied by current-voltage electrical characterization, incident photon-to-electron conversion efficiency, and impedance spectroscopy measurements, showing the promising properties of this material for the fabrication of dye-sensitized solar cell photoanodes with a solar conversion efficiency up to 4.58%. Copyright © 2012 John Wiley & Sons, Ltd.

Electrochemical Impedance Spectroscopy of Metal Oxide Electrodes for Energy Applications

Abstract: Metal oxides have been of great importance to the development of energy conversion and storage technologies including heterojunction solar cells, Li-ion batteries, and electrocatalysts/photocatalys...

Flexible Tactile Sensing Based on Piezoresistive Composites: A Review

Abstract: The large expansion of the robotic field in the last decades has created a growing interest in the research and development of tactile sensing solutions for robot hand and body integration. Piezoresistive composites are one of the most widely employed materials for this purpose, combining simple and low cost preparation with high flexibility and conformability to surfaces, low power consumption, and the use of simple read-out electronics. This work provides a review on the different type of composite materials, classified according to the conduction mechanism and analyzing the physics behind it. In particular piezoresistors, strain gauges, percolative and quantum tunnelling devices are reviewed here, with a perspective overview on the most used filler types and polymeric matrices. A description of the state-of-the-art of the tactile sensor solutions from the point of view of the architecture, the design and the performance is also reviewed, with a perspective outlook on the main promising applications.

Superhydrophobic nanocoatings: from materials to fabrications and to applications

Abstract: Superhydrophobic nanocoatings, a combination of nanotechnology and superhydrophobic surfaces, have received extraordinary attention recently, focusing both on novel preparation strategies and on investigations of their unique properties. In the past few decades, inspired by the lotus leaf, the discovery of nano- and micro-hierarchical structures has brought about great change in the superhydrophobic nanocoatings field. In this paper we review the contributions to this field reported in recent literature, mainly including materials, fabrication and applications. In order to facilitate comparison, materials are divided into 3 categories as follows: inorganic materials, organic materials, and inorganic-organic materials. Each kind of materials has itself merits and demerits, as well as fabrication techniques. The process of each technique is illustrated simply through a few classical examples. There is, to some extent, an association between various fabrication techniques, but many are different. So, it is important to choose appropriate preparation strategies, according to conditions and purposes. The peculiar properties of superhydrophobic nanocoatings, such as self-cleaning, anti-bacteria, anti-icing, corrosion resistance and so on, are the most dramatic. Not only do we introduce application examples, but also try to briefly discuss the principle behind the phenomenon. Finally, some challenges and potential promising breakthroughs in this field are also succinctly highlighted.

Zinc oxide based dye-sensitized solar cells: A review

Abstract: Zinc oxide (ZnO) is the closest alternative to TiO2 as the semiconductor material in a dye-sensitized solar cell (DSSC). This is to be attributed to the facts that both TiO2 and ZnO have same electron affinities and almost the same band gap energies, and ZnO has much higher electron diffusivity than TiO2, a high electron mobility, a large excitation binding energy, is available at low-cost, and stable against photo-corrosion. The article provides a broad survey of ZnO based DSSCs, and highlights the potential of utilizing a ZnO photoanode in the place of a TiO2 photoanode in a DSSC. The merits of a ZnO photoanode, over against those of a TiO2 photoanode, are discussed in detail, associated main problems are mentioned, and their solutions are suggested. Parameters to improve the performance of a DSSC are revealed and solutions to optimize them are suggested. Discussions are made on ZnO based flexible, quasi-solid state, and solid state DSSCs. The advantages and disadvantages of ZnO as semiconductor material in DSSCs are weighed. All architectures reported till date are cited, and the techniques used to achieve such hierarchical structures are mentioned. A thorough discussion is made on the dyes used for ZnO based DSSCs. Organic dyes and metal-free dyes are found to be most suitable for such DSSCs. Optimum particle size of ZnO, its stability, its suitable facet for the application in a DSSC, and the best redox couple for a ZnO based DSSC are discussed with evidences. Great emphasis is given on ZnO films that are doped with various materials. The review also discusses miscellaneous works on ZnO based DSSCs. A hitherto never discussed concept of usage of MOFs in a ZnO based DSSC concludes the review.

In situ MoS2 Decoration of Laser-Induced Graphene as Flexible Supercapacitor Electrodes

Abstract: Herein, we are reporting a rapid one-pot synthesis of MoS2-decorated laser-induced graphene (MoS2-LIG) by direct writing of polyimide foils. By covering the polymer surface with a layer of MoS2 dispersion before processing, it is possible to obtain an in situ decoration of a porous graphene network during laser writing. The resulting material is a three-dimensional arrangement of agglomerated and wrinkled graphene flakes decorated by MoS2 nanosheets with good electrical properties and high surface area, suitable to be employed as electrodes for supercapacitors, enabling both electric double-layer and pseudo-capacitance behaviors. A deep investigation of the material properties has been performed to understand the chemical and physical characteristics of the hybrid MoS2-graphene-like material. Symmetric supercapacitors have been assembled in planar configuration exploiting the polymeric electrolyte; the resulting performances of the here-proposed material allow the prediction of the enormous potentialities...