Spray Pyrolysis Technique Research Articles

Nebulized spray pyrolysis deposited CdO thin films for liquefied petroleum gas and ethanol gas sensor

High quality cadmium oxide (CdO) thin films were prepared through an inexpensive and simple nebulized Spray Pyrolysis (neb-SP) technique. The transparent conducting CdO thin films deposited at different substrate temperatures (TS) for the ethanol and liquefied petroleum gas (LPG) sensor application. XRD, SEM, UV–vis Spectroscopy and Hall Effect were done to study the structural, morphological, optical and electrical properties respectively. Polycrystalline nature thin films shows (1 1 1) cubic structure as the prominent peak. Surface morphology studies reveal that the grain size and roughness of the films are increased with increase in the substrate temperature. The average transmittance of the yellowish transparent CdO thin films is about 57%, thus the films are transparent in the visible region. The optical band gap (Eg) value of the CdO films increased from 2.16 to 2.28 eV with increase in the TS from 225 °C to 300 °C. The minimum value of electrical resistivity of the films is 1.40 × 10−3 Ωcm obtained at 275 °C. The neb-SP deposited CdO thin film (275 °C) shows maximum response to the ethanol and LPG gas sensitivity of 31.87% and 16.4% respectively at operating temperature of 573 K. Thus the results authenticate that the CdO thin films deposited low substrate temperature with high quality can be achieved via neb-SP technique compared to other wet chemical or physical method.

Enhancing π-SnS thin films and fabrication of p-SnS/n-Si heterostructures through flow rate control in ultrasonic spray pyrolysis for improved photovoltaic performance

This study presents findings related to the characterization of cubic SnS (π-SnS) thin films and p-SnS/n-Si heterojunction structures produced simultaneously using the ultrasonic spray pyrolysis technique. In this context, the impact of different spray solution flow rates on the morphological, structural, optical, and electrical characteristics of the films was examined. Morphological analyses revealed that higher flow rates resulted in films with denser and smoother surfaces, approximately 6 nm in roughness. Additionally, it was observed that both the thickness and the growth rate of the films could be adjusted through the modulation of the flow rate. Structural analyses determined that the crystallite size increased and micro-strain values decreased with increasing flow rates. Optical evaluations indicated a decline in the optical band gap of the thin films from about 1.8 eV to 1.7 eV as the flow rates increased. This trend was consistently observed in the data obtained using the Tauc method and the derivative of transmission with respect to wavelength versus photon energy graphs. Electrical analyses revealed that the resistivity values of the thin films increased from 5.24 × 105 Ωcm to 1.64 × 106 Ωcm with increasing flow rates. Furthermore, I-V analyses of the Au/p-SnS/n-Si/Ag heterojunction structures indicated significant variability in key electrical properties. The saturation currents displayed a broad range, suggesting varying efficiencies in charge carrier collection across different samples. Similarly, the change of ideality factors pointed to differences in charge transport mechanisms, while the shifts in barrier heights indicated changes in junction properties with different fabrication conditions. The results of this study offer valuable perspectives for future research.

Enhancing photovoltaic applications through precipitating agents in ITO/CIS/CeO2/Al heterojunction solar cell

In this groundbreaking study, we successfully synthesized both cerium oxide and copper indium sulphate nanoparticles via co-precipitation method and the same is spray coated on ITO substrate by Jet Nebulizer Spray Pyrolysis (JNSP) technique. A comprehensive characterization of the structural, morphological and Photo-diode properties was conducted using a range of advanced techniques. X-ray diffraction revealed a superior mono-crystalline cubic fluorite structure with a preferred orientation along the (111) plane, indicating exceptional crystal quality. Scanning electron microscopy and transmission electron microscopy images showed the formation of disk-shaped particles with sharp rounded edges, averaging ∼ 5 nm in size. Fourier transform infrared spectroscopy identified the phonon band envelope of the metal oxide (CeO2) network at 848 cm−1 while photoluminescence spectroscopy revealed blue and blue-green emission in the visible spectrum. Thermogravimetric-differential thermal analysis exhibited a total weight loss of 19.52 % with four distinct exothermic and endothermic peaks. X-ray photoelectron spectroscopy confirmed the presence of Ce and O elements, with a minor amount of carbon absorbed from the atmosphere and revealed the dominant occurrence of Ce4+ and minority occurrence of Ce3+. The maximum power conversion efficiency of 0.23 % was achieved for samples prepared using NH3 precipitant making them highly suitable for photovoltaic applications. This work paves the way for future research in optimizing cerium oxide nanoparticles for high-performance photovoltaic devices potentially leading to breakthroughs in renewable energy harvesting.

Influence of concentration on optical and structural properties of zinc sulfide films using spray pyrolysis technique

Influence of concentration on optical and structural properties of zinc sulfide films using spray pyrolysis technique

Growth and optimization of spray coated Cu2BaSnS4 thin films for solar photovoltaic application

Quaternary multicomponent Cu2BaSnS4 (CBTS) has emerged as a potential absorber material due to its abundant and nontoxic constituents, high absorption coefficient (10−4 cm−1) and suitable bandgap (1.5–2.0 eV) for the solar photovoltaic application. In this study, polycrystalline CBTS thin layers have been deposited by a typical spray pyrolysis technique on glass substrates using different substrate temperatures (Ts = 200, 250, 300 and 350 °C) followed by annealing in a sulfur-rich atmosphere at 550 °C under an argon flow. The (micro-)structural, compositional, and optical properties of both types of films have been studied. Analysis of x-ray diffractogram (XRD) patterns for all acquired films showed the presence of polycrystalline CBTS alongside various secondary phases, including Cu2SnS3 being predominant. Nonetheless, the XRD of the films deposited at 250 °C and annealed at 550 °C showed only the CBTS phase. Raman spectroscopy confirm the formation of the trigonal phase of CBTS. The presence of Cu, Ba, Sn and S in CBTS thin films was confirmed by X-ray photoelectron spectroscopy and Energy-dispersive X-ray spectroscopy. Scanning electron micrographs show a smooth and dense structure with enhanced crystallinity and improved uniformity. Overall, the physical properties of CBTS thin films were found to be spray deposition temperature dependent. An appropriate optical band gap of 1.6 to 1.8 eV and a compact structure indicate their prospective for solar cell applications.

Study of thin films (ZnO)(0.4)(CdO)(0.6) composite properties

Thin-films (ZnO)(0.4)(CdO)(0.6) composites were grown by the spray pyrolysis technique on glass substrates heated to a temperature of 350°C. The structural properties have been identified using X-ray diffraction spectra. The deposited films are of polycrystalline natures. Both the two materials mixed (ZnO and CdO) were well observed in the X-ray diffraction plot. The optical properties were also studied using UV- Vis optical spectroscopy. transmittance and reflectance are measured in the wavelength range of 200nm to 2500nm. The evaluation of the optical gap shows that this composite has two gaps, the first concerns the ZnO and the second concerns the CdO.

NiO thin films fabricated using spray-pyrolysis technique: structural and optical characterization and ultrafast charge dynamics studies

Nickel (II) oxide, NiO, is a wide band gap Mott insulator characterized by strong Coulomb repulsion between d-electrons and displays antiferromagnetic order at room temperature. NiO has gained attention in recent years as a very promising candidate for applications in a broad set of areas, including chemistry and metallurgy to spintronics and energy harvesting. Here, we report on the fabrication of polycrystalline NiO using spray-pyrolysis technique, which is a deposition technique able to produce quite uniform films of pure and crystalline materials without the need of high vacuum or inert atmospheres. The composition and structure of the NiO thin films were then studied using x-ray diffraction, and atomic force and scanning electron microscopies (SEM). The phononic and magnonic properties of the NiO thin films were also studied via Raman spectroscopy, and the ultrafast electron dynamics by using optical pump probe spectroscopy. We found that the NiO samples display the same phonon and magnon excitations expected for single crystal NiO at room temperature, and that electron dynamics in our system is like those of previously reported NiO mono- and polycrystalline systems synthesized using different techniques. These results prove that spray-pyrolysis can be used as affordable and large-scale fabrication technique to synthesize strongly correlated materials for a large set of applications.

Synthesis and Characterization of Nanostructured Cerium-Doped Zinc Oxide Thin Films for Selective Nitrogen Dioxide Gas Sensing Applications

Zinc oxide thin films doped with cerium were synthesized through facile spray pyrolysis technique and subsequently characterized via an array of analytical methods, including X-ray diffraction, ultraviolet-visible diffused reflectance absorption spectroscopy, photoluminescence, scanning electron microscopy and energy-dispersive X-ray spectroscopy techniques. The operative mechanism of the semiconductor metal oxide gas sensors is predicated on the modulation of electrical conductivity in response to varying gaseous atmospheres, under the influence of disparate thermal conditions. The nitrogen dioxide gas-sensing performance of the films demonstrated a noteworthy gas response of 18% at an elevated temperature of 400°C for a concentration of 100 ppm, accompanied by rapid response and recovery times of 23 and 60 s, respectively.

Investigation on structural and morphological properties of molybdenum trioxide (MoO3) thin films

Abstract The present study reports on the effect of substrate temperature on structural, morphological and optical properties of MoO3 thin films. MoO3 thin films were deposited on pre-heated glass substrate using spray pyrolysis technique. The substrate temperature was varied from 300 °C to 400°C with a step interval of 50 °C. Structural studies were studied using X-ray diffraction technique. It is observed that all the diffraction peaks exactly match with JCPDS card No. 05-0508. The as –deposited MoO3 thin films exhibits orthorhombic crystal structure. It is found that the crystalline nature increases with the increases of substrate temperature. FESEM micrographs show that the grains are distributed uniformly over the surface without any void. An optical property reveals that the transmission of MoO3 thin film in the visible region increases with increases of deposition temperature.

Aerosol-assisted fabrication of mesoporous CeO2 nanoparticles for cargo controlled delivery application

This study presents a spray pyrolysis technique for fabricating mesoporous cerium oxide nanoparticles (MCNs) with tunable properties. The MCNs were extensively characterized by their morphology, crystallinity, optical properties, and surface area through transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectroscopy, UV−vis spectroscopy, and BET adsorption isotherms. We manipulated synthesis parameters to tailor these characteristics, and subsequently evaluated the ability of MCNs to load and release the cationic probe Rhodamine 6G, demonstrating their responsiveness to pH variations. The particles showed high entrapment efficiency (up to 40 %), pH-responsive release, and pore-size-dependent release performance. Additionally, the biocompatibility of MCNs was confirmed by assessing their impact on the viability of HEK293 cells. The findings indicate that the fabricated MCNs hold promise for targeted nano-therapeutic applications, particularly within acidic microenvironments such as tumor sites.

Substrate temperature effect on the structural, morphological and optical properties of pyrolyzed bi-phase Cu2O–CuO thin films

Multiphase nanomaterials are fascinating due to the synergistic effect between the crystalline phases that lead to improved device performance. Publications are available for the synthesis of monophasic copper oxides, such as Cu2O and CuO, and the mixed-phase Cu2O–CuO counterpart using different synthesis methods. However, literature report is scarce that focuses on the fabrication of bi-phase Cu2O–CuO thin films by the spray pyrolysis technique without phase transformation to form the monophasic counterparts. The present work attempts to prepare solely mixed-phase Cu2O–CuO films through small incremental change in substrate temperature, in steps of 20 °C. Structural analysis of the pyrolyzed films revealed the formation of a bi-phase Cu2O–CuO crystal system. The crystallite size increased from 18.64 to 23.94 nm, microstrain decreased from 7.134 ×10−4 to 5.625 ×10−4, while stacking faults decreased from 3.753 ×10−3 to 2.942 ×10−3 with an increase in temperature. Microstructural analysis showed nanoaggregates with increased particle size at increasing temperature. The films exhibited a common optical bandgap of 2.61 eV. The values of the static refractive index and optical electronegativity were found to be 2.47 and 0.70, respectively. The surface roughness increased from 41.3 to 90.9 nm with substrate temperature.

Investigation on the impact of film thickness on spray-deposited Co2SnO4 thin films gas sensing performance towards dimethylamine detection at room temperature

Ternary two-dimensional metal oxide spinel's (A2BO4) have fascinated many researchers due to its inimitable properties such as large reactive surface area, unique phase structure, electrical conductivity, and morphology of the thin film surface. Limitations of a single metal oxide chemi-resistive gas sensor are its higher operating temperature, low detection limit, and long-term stability. In this investigation, a widely employed spray pyrolysis technique is used to deposit different thicknesses of Co2SnO4 thin films. As deposited and annealed films were subjected to all the necessary characterization such as structural, optical, topographical, morphological, and gas sensing performance to understand their performance in real-time application. The synergetic effects of high surface roughness, aggregated porous nanograin morphology, and various physio-chemical properties possibly prompt higher thickness film (A - Co2SnO4) to attain ultrahigh sensor response S = 6074 ± 43, and a good response/recovery time 155 ± 6 s and 44 ± 5 s at 3 ppm at 300 K, respectively. The thin film sensor has excellent long-term stability, repeatability, good moisture resistance, and the lowest detection limit (LOD) with a range of approximately 1 ppm and demonstrates discernible sensor response S = 690 ± 40. These results are the new pathway for tracing dimethylamine gas at room temperature. It can be easily used in food inspection sectors to monitor and detect food freshness.

Effect of post-annealing on structural, optical and electrochemical properties of LiNiVO4 thin films deposited by spray pyrolysis technique

LiNiVO4 films were deposited by spray pyrolysis technique on flexible stainless steel as substrates. The XRD results confirm the formation of LiNiVO4 in a highly crystalline form with an inverse spinel structure after post-annealing the film at 600 °C. From the SEM analysis, it was found that increasing the annealing temperature resulted in the merging of grain boundaries which leads to the formation of larger grains. The bandgap was determined, demonstrating that higher annealing temperatures result in the decrement of bandgap from 2.52 to 2.38 eV. The electrochemical performance of the prepared films was studied using a three-electrode set-up. The LiNiVO4 film annealed at 600 °C exhibited a specific capacitance of 38 F/g at 0.1 A/g current density in 1 M LiOH as an electrolyte.

Comparative analysis of phase coherence length in polycrystalline CdO films on two distinct substrates

The role of substrates in thin film growth encompasses structural and morphological characteristics which, as a consequence, can also affect electronic properties. This article reports studies on the structural, morphological, and magnetotransport properties of Cadmium Oxide (CdO) films grown on two distinct substrates, amorphous glass, and crystalline silicon, by spray pyrolysis technique. The crystallinity of CdO grown on Silicon (CdO/Si) is higher as compared to the CdO grown on glass (CdO/glass), although CdO/Si morphology presents a dome-like surface. In both cases, samples showed exponential behavior in the electrical resistance curves in the temperature ranges between 1.9 K to 300 K and negative magnetoresistance, due to the weak localization effect, for temperatures lower than 110 K. The highest electronic mobility for CdO/Si is attributed to the better crystallinity of the domes. The weak localization effect is correlated by the 3D Kawabata model, fitting the magnetoresistance curves to determine the phase coherence length over a temperature range of 4.2 K to 100 K. Despite the huge differences in the morphological and electrical properties, the linear behavior of temperature-dependent phase coherence length, attributed to the electron-electron interaction in this temperature range, is found to be independent of the employed substrate. This remarkable result indicates the potential application of the low-cost spray pyrolysis technique for producing high-speed photodetectors.

Investigations on temperature dependent properties of spray deposited tin oxide thin films

The present study reported the temperature dependent properties of tin oxide (SnO2) thin films deposited by using conventional, cost effective and non-vacuum-based spray pyrolysis technique (SPT). The as deposited films were characterized by various characterization techniques such as X ray diffraction (XRD), UV-Vis spectroscopy and Scanning electron microscopy (SEM) to study their structural, optical and morphological properties respectively. XRD analysis revealed tetragonal rutile crystal structure of SnO2 with preferred orientation along (200) plane. The refinement of XRD data was also carried out by Rietveld refinement to obtain the fitting parameters, crystallite size and lattice parameters. UV-Vis study showed considerable change in optical absorbance and transmittance with change in substrate temperature. Effect of substrate temperature on film thickness, refractive index and band gap energy were determined by Swanepoel method and by Tauc’s plot respectively. The Urbach energy was also calculated and were correlated to the defects in SnO2 films. SEM micrograph showed the transformation from granules to nanospheres as a function of substrate temperature. Electrical properties were determined by Hall effect measurements which gives carrier concentration, electrical resistivity and mobility in the order of 1019-1020 /cm3, 10−2-10−3 Ω.cm and 4–23 cm2/Vs respectively.

Effect of doping (Sn and In) on CdS thin films for ammonia sensing at room temperature

The quantification and detection of Ammonia (NH3) are crucial due to their direct impact on human health and the environment, particularly when concentrations exceed 50 ppm in the atmosphere. To address this, thin films of pure CdS, Sn-doped CdS (CdS:Sn), In-doped CdS (CdS:In), and co-doped Sn and In (CdS:Sn:In) were prepared using the nebulized spray pyrolysis technique (NSP) for NH3 sensing studies. The X-ray diffraction (XRD) substantiated the single phase and polycrystallinity of the prepared films. Atomic Force Microscopy (AFM) reveals that CdS:In film attained higher RMS, average roughness, skewness (Rsk), and Rku values than the other prepared films. The estimated optical bandgap energy value is 2.44 eV for the CdS:In film. The photoluminescence (PL) studies reveal that the presence of defects. Emission bands observed around 523.35 nm, and 681 nm are attributed to band-to-band transition, and exciton recombination between sulphide vacancies (Vs2+) and the VB respectively. Essentially, the X-ray photoelectron spectroscopy (XPS) analysis reveals the existence of surface elements in various oxidation states. Surpassing the performance of other prepared films, CdS:In exhibited an exceptional response of 604.98 at 250 ppm, long-term stability and good repeatability, with rapid response and recovery times of 43.09 s and 5.6 s respectively.

Characterization of the structure, morphology, and optical properties of titanium dioxide thin film deposited by spray pyrolysis technique for self-cleaning glass

Abstract The research in material science has actively pursued the creation of self-cleaning materials, especially for windows. Titanium dioxide (TiO2) is considered a promising substance for developing hydrophilic self-cleaning surfaces due to its photocatalytic activity. In this research, TiO2 nanoparticles were synthesized using TiCl3 as the precursor and co-precipitation as the experimental method in order to obtain anatase phase. The nanoparticles, then, was deposited by spray pyrolysis technique with different spraying time; 1, 2, 3, and 4 minutes and different types of TiO2 nanoparticles—synthesis and commercial—as the primary variations. TiO2 thin film was formed using ethyl cellulose as binder and isopropyl alcohol as solvent. The synthesized TiO2 nanoparticles and deposited thin film were, then, characterized using XRD, Maud software, UV-Visible Spectrophotometer, optical microscope, and SEM. The higher band gap energy value of TiO2 thin films was obtained with the average of 3.746 eV and 3.744 eV for TI(S) and TI(C), respectively, as a result of ethyl cellulose composition on the thin film. The thin film was categorized as hydrophilic.

Characterisation of Sn-Cl co-doped β-Ga2O3 thin films deposited via spray pyrolysis and their application in UV detector devices

Ga2O3, an ultrawide bandgap semiconducting oxide, is currently emerging as a promising candidate for various applications, such as power devices, solar-blind UV detectors, high temperature oxygen sensors and biomedical imaging. One significant limitation hindering the application of Ga2O3 as a wide-bandgap semiconductor is its poor conductivity. In this work, we investigate whether doping with tin and chlorine can mitigate this condition. Sn-Cl co-doped β-Ga2O3 thin films are deposited on glass substrates using spray pyrolysis technique. The deposited films are subjected to comprehensive analysis, including structural, optical and morphological measurements using techniques like X-ray diffraction, UV-Vis-NIR spectroscopy, X-ray photoelectron spectroscopy and EDX studies. Electrical properties are assessed using the four-probe method and Hall measurements. The best conductivity of 8.86 Ω−1m−1 is observed when 8.68 at% of Sn and 3.37 at% of Cl were co-doped into Ga2O3 (S(3)) and its optical band gap is calculated to be 4.65 eV. This is about five orders of improvement in conductivity as compared to that of pure Ga2O3 thin film deposited by the same method. Furthermore, we have constructed a deep UV detector utilizing doped β-Ga2O3 thin films as the semiconducting absorbing layer. The detector demonstrated the highest responsivity of 2.54 × 10−4 A/W at 260 nm and the corresponding specific detectivity is 1.4 × 109 Jones. The current research validates the potential of Sn-Cl co-doped β-Ga2O3 thin film as an excellent choice for UV detector application.

Enhanced optoelectronic and catalytic properties of Sm doped SnO2 thin films

Herein, we report the optoelectronic and malachite green (MG) aqueous dye model pollutant degradation characteristics of samarium (Sm) doped tin oxide (SnO2:Sm) thin films deposited on glass substrate by chemical spray pyrolysis technique. The tetragonal crystal structure and polycrystalline nature were elucidated from X-ray diffraction (XRD) analysis, and the calculated crystallite size using Scherrer's relation was found to vary between 36 and 45 nm. A high optical transparency of 92 % was achieved for SnO2:Sm (3 wt%). The extrapolation of linear fit indicates a slight decrement in the band gap. Energy dispersive X-ray analysis (EDAX) confirmed the presence of Sn, O and Sm elements and their composition. The quantitative compositional percentage of Sn, O and Sm was determined by X-ray photoelectron spectroscopy (XPS) analysis. The scanning electron micrographs (SEM) showed polyhedron-like shaped grains with cracks and void-free film surface. The 3 wt% Sm:SnO2 thin film exhibited a higher average surface roughness (19.63 nm) than other films. Strong ultraviolet (365 nm), blue (493 nm), and green (520 nm) emissions were observed for all the films, as recorded by photoluminescence (PL) studies. High electron concentration (7.9 × 1020/cm3), low resistivity (0.356 × 10−3 Ω cm), and a high figure of merit (FOM, 5.11 × 10−2 Ω−1) were obtained for 3 wt % of SnO2:Sm thin films. Furthermore, a relatively high photocurrent (8.22 mA) was attained for the 3 wt% Sm:SnO2 thin film. Enhanced photocatalytic efficiency (95 %) was achieved for the 4 wt% Sm:SnO2 film against MG dye aqueous solution. The results obtained in the present study demonstrate high optical transparency, electrical conductivity, enhanced FOM, and photocatalytic degradation efficiency for 3 and 4 wt% Sm-doping, respectively. Therefore, Sm-doped SnO2 could be useful for developing and designing novel devices for optoelectronic and photocatalytic applications.

Study of The Optical Properties of Copper Oxide Thin Films Prepared by Chemical Spray Pyrolysis Technique

Study of The Optical Properties of Copper Oxide Thin Films Prepared by Chemical Spray Pyrolysis Technique