1,720,977 research outputs found
Study of the interaction between the surface of polymeric substrates and chromium thin coatings grown by RF and DC sputtering
No full textAcquisizione in tempo reale dello spettro emesso dalla plume durante un processo di fotoablazione
No full textA Study on Inorganic Metallic and Dielectric Thin Films Grown on Polymeric Substrates at Room Temperature by PVD and CVD Techniques
No full textA Tactile Sensor Device Exploiting the Tunable Sensitivity of Copper-PDMS Piezoresistive Composite
No full textAbstractA low cost and highly mechanically flexible 8x8 pressure matrix sensor with dedicated electronics has been fabricated with an innovative metal-elastomer composite material. Under the action of a compressive stress the material exhibits a giant piezoresistive effect varying its electrical resistance of several orders of magnitude. This phenomenon can be tuned by changing the material composition parameters, directly modifying the sensitivity of the sensor. The micro casting fabrication technique, used for the preparation of self standing sheet of functional material, gives the possibility of easily fabricating complex-shaped structure suitable for integration on robot surface for tactile sensing. The sensor has been tested with a customized electronic circuit after an exhaustive characterization of the functional properties of the material
Photodetection and piezoelectric response from hard and flexible sponge-like ZnO-based structures
No full textStress engineering and optimization of thick garnet crystal films grown by pulsed laser deposition
No full textWe present here results indicating that stress in films grown by pulsed laser deposition (PLD) may be engineered simply by altering the growth parameters of substrate temperature and laser fluence to balance tensile and compressive stresses. Compositional and structural analysis of Gd3Ga5O12 (GGG) films grown on Y3Al5O12 (YAG) substrates, using three different PLD setups and two different ablating lasers, reveal the effects of different growth parameters on residual stress. Some stress reduction strategies were investigated, including slower heating and cooling ramp rates, and amorphous buffer layers, but changing the growth parameters of substrate temperature and laser fluence was found to have a more significant effect. To characterize the evolution of film stress as thickness increases for different laser fluences, three films were grown in stages to allow substrate curvature measurements and X-ray diffraction analysis to be performed every time the thickness had doubled (from 1-16 µm in thickness). The results from these experiments reveal a compressive stress that relaxes with thickness, thought to be due to lattice mismatch, and leads to the conclusion that stress in PLD grown films of GGG on YAG is a balance between lattice mismatch, thermal expansion mismatch and ion-bombardment
Metal oxide nanostructures for the fabrication of efficient DSC photoanodes
No full textThe role of the nanostructured oxide in dye sensitized solar cell photoanode is crucial, towards the development of efficient photoelectrochemical solar harvesters. In fact, the transition from a porous metal oxide film to a nanocrystalline mesoporous one represented the real breakthrough in the development of the first example of dye sensitized solar cell in 1991. Several criteria have to be fulfilled in the optimization of the morphology of the nanostructured material for an efficient light capturing and charge transport at the photoelectrode. The exposed surface for dye sensitization plays a crucial role, since the planar dimension of the dye molecule is significantly higher than its optical cross section and a great number of light capturing centers are necessary to generate a high number of carriers. The electrons injected on the conduction band of the wide band gap semiconductor have to draw a tortuous path when moving on a random assembly of nanoparticles and the possibility to have a direct pathway for the photogenerated charges can reduce significantly the electron recombination. 1D or quasi 1D nanostructures can guarantee a fast and direct charge transport, but usually pay a lot in terms of surface area, being it significantly lower than in nanocrystalline network. Thus, material with a 3D branched nanomorphology with size and spacing on the order of the exciton diffusion length could represent the equilibrium point between the different requirements. In this presentation we give an overview on the application of different metal oxide nanostructures (e.g. TiO2 nanotubes and spongelike ZnO) in the fabrication of efficient DSC photoanodes. TiO2 nanotubes produced by anodic oxidation of Ti foil probably represent the most interesting quasi 1D nanostructure for application in DSC photoanodes. The material synthesis and its integration in front-side illuminated DSC will be illustrated. Moreover, we will report on the synthesis of coral-shaped Zn nanostructured film by radio frequency magnetron sputtering and its treatment in oxidizing atmosphere, leading to the fabrication of spongelike ZnO photoelectrodes with high light conversion efficiency. DSCs were fabricated using both a reversible microfluidic architecture and a standard thermoplastic irreversible sealing. For both materials, particular emphasis will be dedicated to the evaluation of the charge transport properties, showing the reduced charge recombination behavior with respect to standard TiO2 nanoparticle networ
Coral-shaped ZnO nanostructures for Dye Sensitized Solar Cell photoanodes
No full textA 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 characteriza- tion, 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
Metal oxide nanostructures and quasi-solid electrolytes for dye-sensitized solar cells
No full textThe role of the nanostructured oxide in dye sensitized solar cell photoanode is crucial, towards the development of efficient photoelectrochemical solar harvesters. Several criteria, as the possibility to expose a wide surface for dye sensitization and a low recombination behavior during electron transport at the photoelectrode, have to be balanced in the optimization of the morphology of the nanostructured material for an efficient light capturing and charge transport at the photoelectrode. 1D or quasi 1D nanostructures can guarantee a fast and direct charge transport, but usually pay a lot in terms of surface area, being it significantly lower than in nanocrystalline network. Thus, material with a 3D branched nanomorphology with size and spacing on the order of the exciton diffusion length could represent the equilibrium point between the different requirements. Moreover, for the development of solar harvesters exploitable towards an industrial scale, such photoharvesting materials have to be combined with a solid or quasi-solid electrolyte that can guarantee high long-term stability. We will present our recent results on the development of different metal oxide nanostructures (e.g. TiO2 nanotubes and spongelike ZnO) in the fabrication of efficient DSC photoanodes. Particular emphasis will be dedicated to the evaluation of the charge transport properties, showing the reduced charge recombination behavior with respect to standard TiO2 nanoparticle network. Moreover, the application of self standing acrylic-methacrylic membranes prepared by UV-curing as quasi-solid electrolytes will be reported. The evaluation of the photoelectrochemical, structural, and physicochemical characteristics of these electrolytes will be thoroughly discusse
An easy method for the room-temperature growth of spongelike nanostructured Zn films as initial step for the fabrication of nanostructured ZnO
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