Simple Spray Pyrolysis Technique Research Articles

Optical properties of ZnO nano fiber thin films grown by spray pyrolysis of zinc acetate precursor

AbstractGood homogeneous and stoichiometric ZnO nanofiber thin films have been deposited onto cleaned glass substrate by a simple spray pyrolysis technique under atmospheric pressure using zinc acetate precursor at temperature 200 °C. Films of various thicknesses have been obtained by varying the deposition time, while all other deposition parameters such as spray rate, carrier gas pressure and distance between spray nozzle to substrate were kept constant. Surface morphology and optical properties of the as deposited thin films have been studied by Scanning Electron Microscopy (SEM) attached with an EDX and UV visible spectroscopy. From EDX data, atomic weight% of Zinc and Oxygen were found to be 49.22% and 49.62% respectively. The SEM micrograph of the film shows uniform deposition and scattered nano fiber around the nucleation centers. The optical band gap of the ZnO thin films was found to be in the range 3.3 to 3.4 eV and the band gap decreases with thickness of the film. Optical constants such as refractive index, extinction coefficient, real and imaginary parts of dielelectric constants were evaluated from reflectance and absorbance spectra. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Transparent and conducting ZnO films grown by spray pyrolysis

ZnO films were prepared using the simple, flexible and cost-effective spray pyrolysis technique at different substrate temperatures and precursor molarity values. The films' structural, optical and electrical properties were investigated by x-ray diffraction, UV–VIS transmittance spectroscopy, profilometry and voltage–current–temperature (VIT) measurements. The films prepared at substrate temperatures above 400 °C appear better crystallized with (0 0 2) preferred orientation and exhibit higher visible transmittance (65–80%), higher electrical n-type semiconductor conductivity (10–50 (Ω cm)−1), lower activation energy (<0.35 eV) and smaller Urbach energy (80 meV). These results indicate that such sprayed ZnO films are chemically purer and have many fewer defects and less disorder owing to an almost complete chemical decomposition of the precursor droplets. ZnO films having desired optical and electrical properties for cheaper large-area solar cells may thus be tailored through the substrate temperature and the precursor molarity.

Fiber-Optic Near-Field Chemical Sensors Based on Wavelength Scale Tin Dioxide Particle Layers

In this paper, the surprising sensing performance of fiber-optic near-field chemical sensors, based on wavelength scale tin dioxide particle layers, against chemical pollutants in air environment at room temperature are reported. The layers were deposited upon the distal end of standard single-mode optical fibers by means of the very simple, versatile, and low-cost electrostatic spray pyrolysis technique. The morphologic and optical features of the deposited layers were characterized by means of a complex scanning probe system constituted by simultaneous atomic force microscope (AFM) and near-field scanning optical microscope (NSOM). Particle layers composed by tin dioxide grains, with wavelength and subwavelength dimensions, are very promising because they are able to significantly modify the optical near-field profile emerging from the film surface. As matter of fact, a local enhancement of the evanescent wave contribute occurs leading to a strong sensitivity to surface effects induced by the analyte interaction. Here, for the first time to our best knowledge, experimental results on the sensing capability of the proposed chemical probes in air environment are reported. Also, a preliminary study on the effects of the processing stage and the post processing thermal annealing on the film morphology and near-field behavior are presented.

Vertically aligned N-doped carbon nanotubes by spray pyrolysis of turpentine oil and pyridine derivative with dissolved ferrocene

Vertically aligned nitrogen-doped carbon nanotubes were synthesized from the pyrolysis of a mixture of turpentine oil, 4-tert-butylpyridine (C 9H 13N) and ferrocene on silicon and quartz substrate in nitrogen atmosphere at 700 °C by simple spray pyrolysis technique. SEM, TEM, TGA/DTA, Raman spectroscopy, XPS and electron probe micro analysis (EPMA) techniques were used to characterize the structural analysis and composition of the as-grown N-doped carbon nanotubes. Morphology of the films was greatly affected by the nature of the substrate. From the XPS and EPMA data, it was found that nitrogen content of the nanotubes were 1.6 at.% and 2 at.% on silicon and quartz substrate, respectively. Our studies show that two different types of N atoms can be present in these materials. These are ‘pyridinic’ and ‘graphitic’ nitrogen with binding energies of 398.2 eV and 400.4 eV, respectively. Raman spectroscopy reveals that graphitization of carbon nanotubes grown on silicon is better than nanotubes grown on quartz substrate. Thermogravimetric analysis showed that the thermal stability of as-prepared nanotubes grown on silicon substrate is higher than the nanotubes deposited on quartz substrate.

Studies and correlation among the structural, optical and electrical parameters of spray-deposited tin oxide (SnO2) thin films with different substrate temperatures

Abstract Thin films of tin oxide (SnO2) have been grown by using a simple and economical spray pyrolysis technique. The deposition temperature was optimized to 450 °C, while the concentration and quantity of the solution were kept fixed at 2 M and 20 ml, respectively. X-ray diffraction patterns (XRD) studies reveal that the material deposited is polycrystalline SnO2 having primitive tetragonal structure. The lattice parameters, grain size, microstrain and dislocation densities were calculated and correlated with the substrate temperature. The transmission spectra showed a sharp decrease in transmission at the absorption edge and a good form of interference pattern. The figure of merit has been calculated from transmission spectra. Low sheet resistance ∼16.03 Ω/sq cm and high visible transmission (∼86%) were obtained when the films were deposited at the substrate temperature of 450 °C. From electrical measurements, the resistivity was found to be 11.5×10−4 Ω cm, while the carrier concentration was calculated to be 8.81×1021 cm−3.

Investigations on microstructural and optical properties of CdS films fabricated by a low-cost, simplified spray technique using perfume atomizer for solar cell applications

Good quality CdS films were fabricated by employing a simplified spray pyrolysis technique using perfume atomizer. CdS films have been deposited from aqueous solutions of sulphur and cadmium, keeping the molar concentrations of S:Cd = 0.01:0.01, 0.02:0.02, 0.04:0.04 and 0.06:0.06 in the starting solutions. The structural studies reveal that the S:Cd concentration has a strong influence on the microstructural characteristics of the sprayed CdS films. It was found that there is a transition in the preferred orientation from (0 0 2) plane to (1 0 1) plane when S:Cd molar concentration increases. The SEM images depict that the films are uniform and homogeneous. All the films have high optical transmittance (>80%) in the visible range. The optical band gap values are found to be in the range of 2.46–2.52 eV. CdS films fabricated by this simple and economic spray technique without using any carrier gas are found to be good in structural and optical properties which are desirable for photovoltaic applications. Hence, this simplified version of spray technique can be considered as an economic alternative to conventional spray pyrolysis (using carrier gas), for the mass production of low-cost, large area CdS coatings for solar cell applications.

Preparation and characterization of ZnIn2S4 thin films deposited by spray pyrolysis for hydrogen production

Thin films of ZnIn2S4 were deposited onto indium-doped tin oxide (ITO)-coated glass substrates from a mixed aqueous solution of ZnCl2, InCl3 and (NH2)2CS by a simple and economical spray pyrolysis technique. Structural, morphologic and optical properties of the deposited films were characterized by XRD, SEM, and UV–vis spectra. Moreover, the electrochemical and photoelectrochemical properties were studied via Mott–Schottky method, current–voltage measurement, and photocurrent spectrum measurement. It was found that ZnIn2S4 films can be prepared by spray pyrolysis and the grain size obtained was about 120–200nm in diameter. The deposited films have a cubic spinel structure and the optical band gap is about 2.1eV. The results of electrochemical and photoelectrochemical characteristics show that ZnIn2S4 is a potential material for splitting water to produce hydrogen using solar energy.

Elaboration of Transparent Undoped ZnO and Al-Doped ZnO Thin Films by Spray Pyrolysis and their Properties

This work describes the preparation of zinc oxide thin films using a simple and inexpensive spray pyrolysis technique of zinc chloride (ZnCl2) and aluminum chloride (AlCl3) onto glass substrates. Structural, optical, and electrical properties are determined in the temperature range of 350–600 °C. All the films prepared were uniform and well adherent to the substrates, XRD studies showed that the films grow with (002) preferred orientation. Estimated band gap energy from optical absorption data was 3.2–3.4 eV. The measured electrical conductivity at room temperature was found in the order of 10−1(Ω · cm)−1 for ZnO and it is higher by two orders of magnitude for ZnO:Al.

Electrochemical investigations on spray deposited tin oxide thin films

Tin oxide (SnO 2) thin films were prepared by a simple and inexpensive spray pyrolysis technique from an aqueous solution at various substrate temperatures viz. 300, 400 and 500 °C, and their electrochemical studies have been carried out. The thin films have been optically and electrochemically characterized by means of transmittance, cyclic voltammetry and chronoamperometry. The mechanism of reduction and oxidation reactions that took place during the potential cycling is presented. The samples deposited at 500 °C exhibit better performance in terms of coloration efficiency, reversibility, contrast ratio and response time.

Spray-pyrolysis Cd 2SnO 4 films for electrochemical applications

Conductive cadmium stannate (Cd 2SnO 4,) films were grown by a simple spray-pyrolysis technique using aerosols ultrasonically generated from solutions containing Cd(thd) 2(TMEDA) and n Bu 2Sn(AcAc) 2, and monoglyme as solvent (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate, TMEDA = N, N, N′, N′-tetramethylethylenediamine, AcAc = acethylacetonate). The overall film growing procedure was carried out at or below 400 °C thus allowing low-melting temperature materials like glass to be used as film substrates. Typical resistivity values of Cd 2SnO 4 films were found to be ∼ 2 · 10 −3 Ωcm. The films exhibit excellent electrochemical activity with comparable or higher electron transfer rates than cadmium stannate films obtained via sol–gel methods at high annealing temperature.

Effect of post annealing treatment on electrochromic properties of spray deposited niobium oxide thin films

Niobium oxide thin films were deposited on the glass and fluorine doped tin oxide (FTO) coated glass substrates using simple and inexpensive spray pyrolysis technique. During deposition of the films various process parameters like nozzle to substrate distance, spray rate, concentration of sprayed solution were optimized to obtain well adherent and transparent films. The films prepared were further annealed and effect of post annealing on the structural, morphological, optical and electrochromic properties was studied. Structural and morphological characterizations of the films were carried out using scanning electron microscopy, atomic force microscopy and X-ray diffraction techniques. Electrochemical properties of the niobium oxide thin films were studied by using cyclic-voltammetry, chronoamperometry and chronocoulometry.

Electrochromic properties of spray-deposited niobium oxide thin films

Niobium oxide thin films were deposited on the glass and fluorine-doped tin oxide (FTO)-coated glass substrates using simple and inexpensive spray pyrolysis technique. Various preparative parameters like nozzle to substrate distance, spray rate, concentration of sprayed solution were optimized to obtain good substrate-adherent and transparent films. Morphological and structural characterizations of the films were carried out using scanning electron microscopy and X-ray diffraction techniques. Electrochemical characterization of the niobium oxide thin films was carried out using cyclic-voltammetry, chronoamperometry and chronocoulometry.

Effect of substrate temperature on spray deposited CdIn 2Se 4 thin films

Ternary chalcogenides with appropriate bandgap energy have been attracting a great deal of attention because of their potential applications in photovoltaics. CdIn 2Se 4 in the form of thin films is prepared at different substrate temperatures by a simple and economical spray pyrolysis technique. The films have been characterized by PEC, XRD, EDAX, and electrical measurement techniques. The photoelectrochemical characterization shows that both I sc and V oc are at their optimum values at the optimized substrate temperature of 280 °C. The annealing study reveals that the films annealed for 4 h show relatively maximum values of I sc and V oc. The XRD patterns show that the films are polycrystalline with crystallite size 24.8 nm for the film deposited at optimized preparative parameters. Compositional analysis reveals that the material formed is nearly stoichiometric at the optimized substrate temperature. The electrical resistivity measurement shows that the films are semiconducting at minimum resistivity. The thermoelectric power measurement reveals that the thermoelectric power is relatively maximum at substrate temperature 280 °C.

CO sensor derived from mesostructured Au-doped SnO2 thin film

Abstract Pure and Au-doped mesostructured SnO 2 thin films were successfully prepared by using non-ionic surfactant Brij-58 (polyoxyethylene acyl ether) as organic template and tin tetrachloride and hydrogen tetrachloroaurate(III) trihydrate as inorganic precursor. Thin films were deposited onto the glass substrates at 450 °C by simple spray pyrolysis technique. The novel mesostructured tin oxide thin films with different Au concentration exhibit highly selective response towards CO. The correlation of the Au incorporation in the mesostructure with particular morphology and gas sensing behavior is discussed using scanning electron microscopy (SEM), X-ray diffraction (XRD), BET surface area and transmission electron microscopy (TEM) studies.

Effect of Pt concentration on the physicochemical properties and CO sensing activity of mesostructured SnO 2

Pure and Pt-incorporated mesostructured SnO 2 thin films were successfully prepared by using non-ionic surfactant Brij-58 (polyoxyethylene acyl ether) as organic template, and tin tetrachloride and hexachloroplatinic acid as inorganic precursors. Thin films were deposited onto glass substrates at 450 °C by simple spray pyrolysis technique. The mesostructured tin oxide thin films with various Pt concentrations exhibited highly selective response towards CO. The novelty of the present sensor material is its mesostructured nature with high sensitivity and selectivity towards CO at 200 °C. The correlation of the platinum incorporation in the mesostructure with morphology and structure is discussed based on the results of scanning electron microscopy (SEM), X-ray diffraction (XRD), BET surface area, transmission electron microscopy (TEM) and gas sensing behavior.

Effect of substrate temperature on electrochromic properties of spray-deposited Ir-oxide thin films

Electrochromic iridium oxide thin films were prepared by using a simple and inexpensive spray pyrolysis technique onto fluorine doped tin oxide (FTO)-coated glass substrates, from iridium chloride solution. The substrate temperature was varied between 250 and 400 °C. The as-deposited samples were amorphous. The electrochromic properties of thin films were studied in aqueous electrolyte (0.5N H 2SO 4) using cyclic voltammetry (CV), chronoamperometry (CA) and spectroelectrochemical techniques. The films exhibit anodic electrochromism upon intercalation and deintercalation of H + ions. The colouration efficiency at 630 nm was calculated and found maximum for I 250 sample, owing its hydration.

Properties of spray-deposited CdIn2Se4 thin films for photovoltaic applications

Thin films of cadmium indium selenide have been deposited onto amorphous glass substrates using a simple and low-cost spray pyrolysis technique. The aqueous solutions containing precursors of Cd, In and Se have been used to obtain good quality deposits at optimized substrate temperature. The preparative parameters such as concentration, substrate temperature, etc. have been optimized by photoelectrochemical technique. The films have been characterized by techniques such as X-ray diffraction, scanning electron microscope, EDAX and electrical characterization. The photoelectrochemical characterization shows that both short-circuit current (I sc ) and open-circuit voltage (V oc ) are at their optimum values at the optimized substrate temperature of 280C and concentration (0.0125 M). The XRD patterns show that the films are polycrystalline with cubic structure. The SEM studies reveal the compact morphology with large number of grains. Compositional analysis reveals that the material formed is nearly stoichiometric at the optimized preparative parameters. The electrical resistivity shows that the films are semiconducting and the resistivity is found to be minimum at optimized substrate temperature. The thermoelectric power (TEP) measurement reveals that the TEP is relatively maximum at same substrate temperature of 80°C. Photovoltaic output characteristics study reveals that the fill factor and efficiency; to be 69% and 3%, respectively.

Thin films of photocatalytic TiO 2 and ZnO deposited inside a tubing by spray pyrolysis

Thin films of photocatalytic TiO 2 and ZnO were deposited in Vycor tubing by a simple and reproducible spray pyrolysis technique. Films were transparent and non-light scattering. Film characterization by transmission electron microscopy shows that titanium oxide films were polycrystalline and that their structure corresponded to the tetragonal anatase phase. In addition, ZnO films were polycrystalline with a structure that belonged to the hexagonal Wurtzite type. The solar photocatalytic efficiency for butane degradation was compared to that of Degussa P-25 TiO 2 powder (P-25). Reaction rate and reaction order were obtained from butane concentration measurements using the tubing as a non-circulating reactor exposed to solar radiation. The best fitting was obtained for a pseudo-first order rate constant. The TiO 2-covered tubing shows very high photocatalytic activity, even higher than that of P-25, if activity per unit of catalyst mass is considered.

Preparation and characterization of spray pyrolyzed nickel oxide (NiO) thin films

A simple and inexpensive spray pyrolysis technique (SPT) was employed to deposit nickel oxide (NiO) thin films from hydrated nickel chloride salt solution on to glass substrates. The thermogravimetric analysis (TGA) and differential thermal analysis (DTA) techniques were used to study the thermal characteristics of the precursor salt. The effect of the volume of sprayed solution on structural, optical and electrical properties was studied using X-ray diffraction (XRD), infrared (IR), optical absorption, electrical resistivity and thermoelectric power (TEP) techniques. It is found that increase in the volume of sprayed solution leads to the increment in film thickness and amelioration of crystallinity of the film, consequently the band-gap energy wanes from 3.58 to 3.4 eV. It also affects resistivity and TEP of the film.

Deposition of highly oriented ZnO films by spray pyrolysis and their structural, optical and electrical characterization

Thin films of zinc oxide (ZnO) have been deposited onto glass substrates using a simple and inexpensive spray pyrolysis technique. A nonaqueous methanolic solution of zinc acetate was used as a spraying solution. The concentration of the solution was varied between 0.025 to 0.4 M. The films prepared at different solution concentrations were uniform and well adherent to the substrates. X-ray diffraction (XRD) studies showed that all the films were polycrystalline having hexagonal wurtzite-type crystal structure with strong orientation along (002) plane except 0.025 M, which exhibits a strong orientation in along (100) plane. The bandgap energy, electrical resistivity and thermoelectric power of the films were found to be dependent on the solution concentration. As solution concentration increases, the bandgap energy attenuates from 3.33 to 3.24 eV. The room temperature electrical resistivity was found to be vary in the range 10 2 to 10 −3 Ω cm, whereas thermoelectric power increases from 1×10 −6 to 8×10 −5 V/K. All the films showed n-type conductivity as evidenced from thermoelectric power (TEP) measurement.