Recent studies have shown spray-pyrolysis is a low-cost, simple and efficient technique for deposition of metal oxide semiconductors (such as zinc oxide) as the active layer of thin-film transistors (TFTs). However, to allow the translation from laboratory scale to industry the reproducibility of such method needs to be evaluated. We present herein a representative study concerning the reproducibility and uniformity of spray-coated ZnO TFTs using several devices, from different production batches, following the same fabrication protocol. We demonstrate that it is possible to obtain transistors with high performance and reproducibility by controlling the most relevant deposition factors, corroborated by a low deviation rate (below 10%) from the characteristic TFT parameters (mobility in saturation, threshold voltage and on/off ratio), which is compatible to commonly available commercial electronic devices.

This study reports on the effect of introducing TiO2 compact layer on the photovoltaic characteristics of TiO2/Nb2O5 composite dye sensitized solar cell. The compact layer was deposited by spray pyrolysis technique. It was observed that introduction of 60 nm thick compact layer improved the short circuit current density Jsc ,Open circuit voltage Voc, and efficiency of the cell from 4.9 mA/cm2 to 8.2 mA/cm2, 6.8×10-1 V to 7.2×10-1 V and 1.9 % to 3.4 % respectively compared to traditional cell prepared without compact layer. Electrochemical impedance spectroscopy confirmed an increase in recombination resistance from 5.5×101 Ω.cm2 for bare DSSC to 9.0×101 Ω.cm2 for DSSC with compact layer thereby improving electron lifetime of the cells from 2.5×10-4 s to 386.9×10-4 s.

To free ourselves from the use of fossil fuels that are highly polluting, life-threatening and not easily regenerated, new technologies are being developed to obtain alternative energy sources more efficiently. Among these technologies, there is the option to improve the performance of solid oxide fuel cells (SOFCs) to make them highly energy efficient. Solid oxide fuel cells (SOFCs) have attracted much attention because they are environmentally benign, sustainable, generate low emissions and have relative low cost. However, conventional SOFCs with yttria-stabilized zirconia (YSZ) electrolyte require high operating temperatures (800-1000°C), which often lead to material degradation problems. Given that the greatest disadvantage of SOFCs is their high operating temperature, samples of CeO2 were synthesized by spray pyrolysis method and doped with Sm2O3 and Eu2O3 to improve the ionic conductivity of the electrolyte so that it can operate at lower temperatures without losing its efficiency. The samples were analyzed using SEM, EDS, TEM. Further research will be made by small angle DRX, AFM, EIS and a prototype will be built to test the working temperature of the electrolyte.

Metal oxides like zinc oxide (ZnO) are promising materials for the active layer of thin-film transistors (TFTs) used in the drive circuit of next-generation large-area active matrix displays due to their high electronic mobility, high transmittance in the optical visible range and processability. Traditional deposition techniques employ RF sputtering or pulsed-laser deposition (PLD), which are relatively sophisticated techniques. The deposition of very thin (less than 50 nm thick) layers of ZnO using soluble organic precursors have been extensively investigated recently as an alternative to traditional deposition methods. Solution-based deposition processes include simple and affordable techniques like dip-coating, spin-coating, spray-pyrolysis and ink-jet printing. Spray-pyrolysis is particularly interesting due to the high film uniformity, low cost and high device performance. We carried out several experiments analyzing the performance of ZnO based devices using zinc acetate as organic precursor to confirm that spray pyrolysis deposition is a suitable technique for production of high-performance and reproducible TFTs. Moreover, we observed that device performance can significantly vary with little modifications on the deposition parameters, even for the same active layer composition and pyrolysis temperature. Electrical parameters, as the electrical mobility and the on/off ratio, varied several orders of magnitude, whereas the threshold voltage varied up to 20 V for the tested devices. Deposition parameters as the nozzle height during the deposition, nozzle air pressure and deposition time were varied until we obtained devices with optimum electrical performance. Optimized devices presented mobilities in the order of 1 cm2.V-1.s-1, on/off ratio of about 106 and relatively low operation voltages. A statistical analysis of a great number of devices manufactured using the same deposition parameters was also carried out to assure the reproducibility of the deposition technique.

In this work, we present the optoelectronic characterization of pure tungsten oxide nanoparticle networks synthesized and self-assembled by flame spray pyrolysis. Current-voltage measurements performed in dark conditions indicate the presence of trapping and de-trapping phenomena from defects inside the energy gap. The presence of defects is confirmed by the time evolution of the photocurrent, measured under monochromatic radiation at 420 nm. After illuminating the WO3 films with light, the current increases exponentially with a time constant independent on the applied voltage. This behavior is ascribed to the presence of defects lying at 1.1 eV below the conduction band of WO3 (bandgap of ca. 2.9 eV). When the illumination is terminated, the photocurrent shows an exponential decrease, once again independently on the applied voltage. The defect level corresponding to this relaxation process corresponds to 0.92eV below the conduction band.

Nowadays, carbon nanotubes have a lot of applications in daily life, being applied in the fabrication of cellphones, computers, nanotransistors, among many others. Currently, their new applications in biotechnology area are in research, in particular in order to find new biosensors with fluorescent properties applying on the basis of multi-wall carbon nanotubes (MWCNTs). In this work, the obtaining of carbon nanoparticles having fluorescent properties via spray pyrolysis is presented. Synthesis, properties, structural peculiarities, and applications of nanobuds and related nanostructures are discussed. MWCNTs, decorated with strontium aluminate SrAl12O19 and doped with rare-earth elements, were synthetized from distinct organic precursors and the corresponding metal oxides. The metal oxides used were Samarium (Sm), Europium (Eu), Neodymium (Nd), Lanthanum (La), Cerium (Ce) and some their combinations.

The synthesis was carried out on the surface of optical fibres to obtain a uniform growth of forest-like MWCNTs, adding to metal oxide nanoparticles to their surface. The preparation of composites was carried out by spray pyrolysis techniques in dry nitrogen atmosphere in the temperature range from 780 to 850°C. The formed products were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), FTIR spectroscopy, Raman spectroscopy and UV/visible spectroscopies. The analysis of the obtained data shows that the deposited nanoparticles are in the range of size 20-60 nm being uniformly distributed on the surface of MWCNTs. The samples, obtained at different temperatures and with doping metal oxides added to SrAl12O19, show different fluorescence behavior. The best results were observed with lanthanum oxide as a dopant. Possible applications as persistently luminescent phosphors for the formed MWCNTs-supported luminescent materials are proposed.

In the current work, we evaluate the influence of the processing parameters on the electrical properties of aluminium zinc oxide (AZO) thin films produced by airbrush spray-pyrolysis deposition technique. Spray-deposited AZO thin-films were produced with Al:Zn molar ratios varying from 0 % (pure ZnO) up to 30 %, using aluminium acetate and zinc acetate as organic precursors and water as solvent. Thermogravimetric analysis (TGA) and infrared spectroscopy (FTIR-ATR) were used to monitor the metal-oxide formation from the organic precursors as a function of the temperature. The results show that a temperature of 400 °C is necessary to completely degrade the organic phase and to obtain the desired inorganic metal-oxides films. The electrical properties of the TMOs were evaluated by d.c. current-voltage (I-V) analysis using planar thermally evaporated Al electrodes on top of the TMO layer, with different aspect ratios (1/18, 2/9, 5/13, 5/9 and 8/9). The lowest sheet resistance was obtained for AZO films at a molar Al concentration of 5 %. We also observed that, after carrying out a post-annealing treatment (30 mbar, 150 °C) the samples presented a decrease on the sheet resistance superior to 60 %, in comparison to the samples before the treatment.

High iodine containing oxides are of interest as biocidal components in energetic applications requiring fast exothermic reactions with metallic fuels. Aerosol techniques offer a convenient route and potentially direct route for preparation of small particles with high purity, and are a method proven to be amenable and economical to scale-up. Here, we demonstrate the synthesis of various iodine oxide/iodic acid microparticles by a direct one-step aerosol method from iodic acid. By varying temperature and humidity, we produced near phase pure δ-HIO3, HI3O8, and I2O5 as determined by X-ray diffraction. δ-HIO3, a previously unknown phase, was confirmed in this work. In addition, scanning electron microscopy was used to examine the morphology and size of those prepared iodine oxide/iodic acid particles and the results show that all particles have an irregularly spherical shape. Thermogravimetric/differential scanning calorimetry measurement results show that HIO3 dehydrates endothermically to HI3O8, and then to I2O. I2O5 decomposes to I2 and O2.

SnO2 doped with Sb and Nb has been investigated for its use as catalyst support materials replacing carbon to enhance PEM fuel cells stability. Nanostructured powders of various doping levels were prepared by flame spray pyrolysis (FSP). The specific requirements of surface area >50 m2g-1 and electronic conductivity >0.01 Scm-1 were obtained, and pore sizes ranging mainly from 10 to 100 nm. Pt particles (9-20 wt.% in loading targeted) of ∼1 nm well dispersed in Sb-doped SnO2 was prepared by a one-step FSP procedure providing microstructures of high interest for further investigations as cathode in PEM fuel cells.

Doped hafnium oxide (X-HfO2, X= Eu, Tb, Dy) thin films were deposited by experimental ultrasonic spray pyrolysis process. Doped Hf nano crystal (nc-X-Hf) embebed in the HfO2 matrix were obtained. The process was made at substrate temperature between 300 °C and 550 °C, showing at this higher temperature the monoclinic phase, which improve the dopants incorporation. Computational simulations were made to analyze molecular dynamics in advance to improve physical and chemical properties. Energy relaxation, and charge distribution behaviour demonstrated an atomic re-arranged to form the nano clusters of 5nm to 10 nm diameter. Vibrational modes were calculated. Photoluminescence (PL) spectra were obtained, as dopant function. Atomic Force Microscopy (AFM), X-ray diffraction and High Resolution Transmission Electron Microscopy (HRTEM) characterizations were made. Characteristics bright peaks appear in the Thermoluminescence (TL) spectra, and PL peak emission as well, of the Eu, Tb, Dy dopants in the HfO2 matrix. The results obtained show that nanocrystal structures embebed in a metal oxide matrix of HfO2 could be a prominent material to be used in radiation dosimetry, technological development, and radiological protection.

A continuous process was developed to synthesize submicron boron carbide particles from boric acid and sucrose-based precursor solutions using a home-made spray pyrolysis system. A control set of samples was also prepared for comparison purposes of the microstructure and morphology of the ones synthesized via the spray pyrolysis method. Moreover, nickel nitrate was used in a precursor solution to investigate its catalyst effects on the reaction kinetics of boron carbide formation. The boron carbide phase was observed in the particles synthesized with spray pyrolysis at a reactor temperature of 1550 °C. The average particle size was approximately 0.46 μm. No effect of nickel additions was observed as a catalyst in boron carbide formation. Computational fluid dynamics software was used to model and simulate the experimental system. Simulation results provided information about the residence time and the temperature distribution along the tube reactor.

The synthesis technique that can be used to accelerate the discovery of materials for various energy conversion and storage applications is presented. Specifically, this technique allows a rapid and controlled synthesis of mixed metal oxide particles using plasma oxidation of liquid droplets containing mixed metal precursors. The conventional wet chemical methods for synthesis of multimetal oxide solid solutions often require time-consuming high pressure and temperature processes, and so the challenge is to develop rapid and scalable techniques with precise compositional control. The concept is demonstrated by synthesizing binary and ternary transition metal oxide solid solutions with control over entire composition range using metal precursor solution droplets oxidized using atmospheric oxygen plasma. The results show the selective formation of metastable spinel and the rocksalt solid solution phases with compositions over the entire range by tuning the metal precursor composition. The synthesized manganese doped nickel ferrite nanoparticles, NiMn z Fe2−z O4 (0 ≤ z ≤ 1), exhibits considerable electrocatalytic activity toward oxygen evolution reaction, achieving an overpotential of 0.39 V at a benchmarking current density of 10 mA/cm2 for a low manganese content of z = 0.20.

We employed ultrasonic spray deposition method for production of high quality FTO thin film TCOs to be employed in a silver embedded grid type and monolithic type dye sensitized solar modules. Produced films exhibited dense and crystalline structure with homogeneous coverage on solar glass substrates. Obtained resistivity and light transmission values of FTO are comparable to commercially available FTO coated glasses used widely in the industry. After optimization of the chemistry and deposition conditions, 10x10 cm sized glass substrates could be produced for large area photovoltaic modules. Produced FTO films were used to construct monolithic type and parallel type dye sensitized solar modules. Monolithic modules yielded 1.61% active area efficiency value. In order to enhance the active area of the parallel type modules, silver grid lines were embedded in glass substrate and FTO coating was deposited on the lines. Due to this effective design, we achieved 2.42% efficiency on the total area of the 55x55 mm sized module compared to 2.90% active area efficiency, proving that this design is suitable for enhancing efficiency values of parallel type dye sensitized solar modules.

AIZO (Al and In codoped ZnO) thin films were deposited on soda lime glasssubstrates by the ultrasonic spray pyrolysis (USP) technique. The sprayingsolution was prepared from zinc acetate dihydrate, aluminum acetyl acetonate andindium acetate. Depositions were carried out at three different temperatures,425, 450 and 475 °C. Structural, morphological, optical and electricalproperties were examined with respected to the deposition temperatures. All AIZOfilms grown with (002) preferential orientation confirmed from X-ray diffractionanalysis. Hexagonal nanostructures were observed from Scanning electronmicroscopy (SEM) analysis. Minimum electrical resistivity of 2.52x10-3 Ω-cm was achieved for AIZO films.

Thin films of TiO2/SnO2:F multilayers were prepared by spray pyrolysis technique on glass substrate. The samples were prepared using titanium (IV) isopropoxide 98%, ammonium fluoride and tin(II) chloride dehydrate extra pure as precursor materials. Thus, a TiO2 thickness dependence optical study of TiO2/SnO2:F/glass system is presented. The optical property was characterized by UV-Visible transmittance spectroscopy. For all the samples, the average transmissions in the visible wavelength region (400-800 nm) were between 69 and 84%. The optical parameters, such as the real part dielectric function ε1 and the imaginary part dielectric function ε2, of TiO2 and SnO2:F in the TiO2/SnO2:F thin films structure, determined by fitting the measured optical transmittance spectra, are presented and analyzed. Among the various classical dispersion relations for the dielectric function, the Drude model combined with the Lorentzian oscillators was used to get a good fit of transmittance in the measured spectral range. Results on related parameters such as high frequency dielectric constant, plasma frequency, film thickness and band gap are presented.

Surfactant-free SnS nanoparticles were synthesized using continuous spray pyrolysis (CoSP) technique and used as sensitizers on electro-deposited ZnO nanowire arrays for fabrication of extremely thin absorbing (ETA) layers. The high-surface-area nanowire layer on ITO substrate was directly over-coated by SnS nanoparticles. The morphology of the ZnO/SnS nanostructures showed the coverage of orthorhombic SnS nanocrystals on hexagonal ZnO prismatic nanowires. The crystalline phase of the ZnO/SnS nanostructures was studied using X-ray diffraction. Conducting AFM showed a nonlinear characteristics confirming the junction formation.

In this work, the annealing effects at 180°C in Aluminum-ZnO contacts as function of time were studied. Also, the application in TFTs of ZnO films obtained at low-temperature (200°C) are presented. The ZnO films obtained by ultrasonic Spray Pyrolysis at 200 °C were deposited over Aluminum contacts on SiO2/Si wafers to demonstrate the use of active layer in thin-film transistors. The results show that an improvement can be obtained in metal-ZnO interfaces by low-temperature annealing treatments. However, long annealing time degrade the metal-ZnO interface and may affect the electrical performance of the device.

According to the reports of Z.E. Horvath et al [1] and Liu Yun-quan et al [5], carbon nanotubes can be synthesized by spray pyrolysis from different carbon sources (n-pentane, n-hexane, n-heptane, cyclohexane, toluene and acrylonitrile) and several metallocene catalysts (ferrocene, cobaltocene and nickelocene). This paper describes two different existing methods for growth of carbon nanotubes and the influence of applied parameters (oven temperature, synthesis time, catalyst concentration, carrier gas flow and solution flow) on the CNT's morphology. Also, a possible influence of number of carbons in carbon sources and structures of their compounds (linear or aromatic) on properties of formed carbon nanotubes. Transmission Electron Microscopy (TEM), Infrared Spectroscopy (FTIR) and Raman spectroscopy were applied for characterization of obtained materials.

Spray pyrolysis has been widely used to prepare homogeneous and uniform ceramic powders with high purity. In this study, we are proposing ultrasonic spray pyrolysis followed by heat treatment to produce SiOx/C composite powders, where sucrose was used as a carbon source. Furthermore, high energy ball milling of the as-prepared powders in the presence of acetylene black was conducted to activate its electrochemical properties by reducing the particle size and improving the functionalization of the SiOx composite particles. SiOx/C nanocomposite finally obtained at a sucrous concentration of 0.1 mol L-1 showed superior electrochemical properties, and the SiOx/C nanocomposite electrode delivered the first discharge and charge capacities of 1252 and 819 mAh g-1, respectively, with an initial columbic efficiency of 65% at a current density of 50 mAh g-1 in the potential range from 0.01 to 3 V versus Li/Li+.

A novel approach to fabricate CuIn(S,Se)2 (CIS) thin films through ultrasonically spraying a hydrazine-based precursor solution onto a heated substrate is reported. The effects of the composition of the precursor solutions and the deposition temperature on the CIS film properties were investigated by comparing thin films fabricated using aqueous metal salt solution, anhydrous hydrazine solution, and hydrazine hydrate solution at various deposition temperatures. Crystallite size and texture coefficient in the preferred (112) orientation in the sprayed films increased when the aqueous solution was replaced by hydrazine-based solutions. Additionally, the hydrazine-based precursor solutions resulted in films with better surface smoothness and compositional uniformity than those fabricated using water-based solutions and the hydrazine hydrate solution resulting in the smoothest, most uniform films. The sprayed films were used to fabricate preliminary solar cells that demonstrated a modest photovoltaic response. With optimization, the synthesis of high-quality CIS films by spray pyrolysis from a hydrazine hydrate solution could demonstrate the potential for a low-cost, high-throughput manufacturing process.