Spray Pyrolysis Deposition Research Articles

2-Axis controlled spray pyrolysis deposition device for Dye-sensitized Solar Cell (DSSC)

Dye-sensitized solar cells (DSSCs) are a promising alternative to traditional silicon-based photovoltaic systems due to their efficient light-to-electricity conversion. A critical component of DSSCs is titanium dioxide (TiO2), responsible for converting light into electrical energy. Spray pyrolysis was one of the methods for fabricating TiO2 thin films. However, there are several drawbacks, such as challenges in particle size control, maintaining homogeneity of the thin film, and scalability issues during the deposition process. Modifications to the manufacturing process are necessary to achieve optimal performance in DSSCs, particularly with the thickness of the cell. This work focuses on the 2-axis spray pyrolysis process, a cost-effective way to create thin and thick films. In particular, it focuses on TiO2 thin films utilized as working electrodes in DSSC applications. The method was performed at different motor speeds, namely MS80, MS100, and MS120. The X-ray diffraction (XRD) spectrum showed that the dominance of the anatase phase appeared in an MS100. The UV-Vis results depict that the band gap value is 3.02 eV. The surface profiler analysis indicates that sample MS100 has an optimal thickness of 15.17 µm. The DSSC achieved 9.4% efficiency with sample MS100. This finding demonstrates that using 2-axis controlled spray pyrolysis deposition improves DSSC performance with an optimal motor speed.

Microstructural and optical properties of nanostructured Al/Ag co-doped ZnO thin films (AgxAl0.03ZnO0.97-x) by spray pyrolysis for optoelectronic applications

Al/Ag co-doped ZnO (AgxAl0.03ZnO0.97-x, x = 0, 0.02, 0.04, 0.06, 0.08) thin films were prepared using a facile spray pyrolysis deposition route, and their microstructural and optical properties were investigated. Dislocation density reduced and film crystallinity improved with increasing Ag content. This correlated with strain relaxation (∼10−4) and crystallite size enlargement (>23 nm) at high Ag concentrations, as determined by the Scherrer, Williamson-Hall, Halder-Wagner, and Wagner-Agua approximations. The small Urbach energy (<321 meV) and narrow band gap (∼3 eV) observed at low Ag concentration (4 at.%) indicate less structural defects and disorder, and facilitate exciton dissociation with minimum recombination, respectively. The Moss, Herve and Vandamme, and the Ravindra and Gupta models exhibited high correlation between refractive index values (2.09–2.35). Thus, this study demonstrates the enormous potential of Al/Ag co-doping to advance the properties of ZnO films to suit the fabrication of optoelectronic devices, and create opportunities for commercialization.

Design and optimization of self-assembled nanocomposite electrodes for SOFCs

Nanocomposites exhibit improved electrochemical and mechanical properties compared to single-phase materials, making them promising for the development of efficient and durable electrodes in solid oxide fuel cells (SOFCs). However, conventional fabrication methods usually involve multiple steps and high sintering temperatures, potentially leading to adverse effects on the properties of these materials due to excessive grain growth or reactivity among the cell components. In this study, nanocomposite electrodes of Sm0.5Sr0.5CoO3-δ - Ce0.9Sm0.1O1.95 (SSC–CSO) are prepared using a co-synthesis freeze-drying method, followed by screen-printing deposition and sintering at high temperatures. Alternatively, they are prepared through direct spray-pyrolysis deposition on the electrolyte at reduced temperatures. In both cases, the intimate mixture of SSC and CSO phases not only partially suppresses grain growth but also provides extended actives sites for the electrochemical reactions. More interestingly, when the electrodes are directly assembled onto the electrolyte via spray-pyrolysis, no adverse chemical interaction between the SSC and CSO components is observed, unlike the screen-printed electrodes. These nanocomposite electrodes exhibit remarkably high thermal stability during annealing cycles at intermediate temperature. Polarization resistance values as low as 0.09 Ω cm2 are achieved at 600 °C, further decreasing to 0.04 and 0.015 Ω cm2 under cathodic and anodic polarization, respectively.

Synthesis and Characterization of ZnO-CuO Nanocomposites Thin Film for Optoelectronics Applications

In this work, the spray pyrolysis technique on glass substrates at 480°C was effectively used to generate ZnO, CuO, and n-ZnO/p-CuO nanocomposite thin films. The structure of the ZnO thin films exhibited a hexagonal wurtzite type. In the visible region of the spectrum (400–700 nm), the resulting films had optical transmission ranging from 73% to 83% and optical band gap fluctuations of 3.23 to 3.25 eV. Analysis of the m-lines spectroscopy revealed that the obtained thin layers (ZnO, ZC3, and ZC7) exhibited two modes for both TE and TM polarizations across different molar percentages. This observation confirms the efficacy of the spray pyrolysis deposition technique in producing high-quality waveguides based on ZnO.

Interfacial carbon quantum dot thin film impacts on morphological and chemical structures of fluorine-doped tin oxide films

Morphology and chemical bonding states, including surface roughness, film density, F-doping, and oxygen vacancy (VO) concentration directly affect the electrical and optical properties of fluorine-doped tin oxide (FTO) films. In this study, morphology and chemical bonding states of FTO films are engineered simultaneously by introducing a carbon quantum dot (CQD) thin film as an interface layer during ultrasonic spray pyrolysis deposition. The abundant oxygen-containing surface functional groups and large surface free energy of the CQD thin film promoted (200) oriented crystal growth and accelerated nucleation of FTO, resulting in smooth and dense FTO film morphology. The abundant carboxyl surface functional groups on the CQDs generate active F− species that are effectively doped into SnO2. Formic acid, formed by dissociation of the carboxyl group, can serve as a strong reducing agent for extracting oxygen atoms from the SnO2 lattice, thereby increasing the VO concentration. The accelerated F-doping and VO concentration result in the generation of additional free electrons. The effects of the optimized CQD on the morphological and chemical structures of FTO films are demonstrated by their superior electrical (sheet resistance of ∼5.7 Ω/□) and optical properties (visible transmittance of ∼85.9 %) compared with bare FTO. Moreover, CQD/FTO used as transparent conducting electrodes in electrochromic (EC) application exhibited improved EC performances, including fast switching speeds (5.3 s and 2.3 s for bleaching and coloration, respectively) and high coloration efficiency (81.1 cm2/C) compared to that of bare FTO.

A Study of Deposition/Annealing Cyclic Method to Enhance the Performance of Zinc-Tin Oxide Thin-Film Transistor by Ultrasonic Spray Pyrolysis Deposition

A Study of Deposition/Annealing Cyclic Method to Enhance the Performance of Zinc-Tin Oxide Thin-Film Transistor by Ultrasonic Spray Pyrolysis Deposition

Investigating electrical properties and crystal growth in NiO thin films by spray pyrolysis and electrostatic spray deposition

The control of the electrical properties and the growth mechanism of the NiO films were investigated by Li addition using the spray pyrolysis method. In addition, to enhance the uniformity and flatness of the NiO films, the electric field applied spray pyrolysis named electrostatic spray deposition (ESD) process was applied. Experimental results suggest that a certain amount of Li acts as an interstitial on the Ni sites in the NiO film and enhances crystal growth. Moreover, excessive Li additions resulted in Li segregation into NiO crystal defects, whereas the resistivity decreases and the promotion of crystal growth was not inhibited regardless of the presence of Li on the NiO film up to a Li concentration of 10 at.%. Furthermore, ESD was confirmed to deposit highly flat NiO films. These results represent the initial step toward the practical application of visible-light-transparent devices using spray deposition.

Low-temperature growth of BaZrO3 and Ba(Zr,Y)O3−δ thin films via spray pyrolysis deposition

BaZr1−xYxO3−δ (BZY) is a promising electrolyte for proton-conducting oxide fuel cells. However, the fabrication of BZY requires high-temperature processing (> ∼1700 °C) for densification, which makes the fabrication process expensive and may lead to degradation in fuel cell performance due to atomic diffusion at the electrode interface. To address these issues, this study focused on the deposition of BaZrO3 and BZY thin films via spray pyrolysis using an acetylacetonate-based precursor solution. Single-phase BaZrO3 thin films, featuring a columnar structure and preferential (100) orientation, were obtained at a substrate temperature of 800 °C in a 5 % O2 atmosphere. The BZY thin films could be obtained by incorporating Y into the precursor solution, and the composition of the thin films could be modulated by adjusting the precursor solution composition. No diffusion of Ni into the BaZrO3 thin film was observed when the BaZrO3 thin film was deposited on a NiO-BZY substrate at 800 °C. This suggests that the spray pyrolysis deposition of BZY thin films is an effective approach for fabricating a junction structure between the BZY electrolyte and electrode while avoiding atomic diffusion at the interface.

Temperature dependence of spray pyrolysis deposited NiOx layer in inverted perovskite solar cells

Abstract The impact of NiOx layers on the performance of inverted perovskite solar cells (PSCs) has been investigated using multiple analysis methods (thermal gravimetric, differential thermal analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and Soft X-ray photoelectron spectroscopy) of NiOx layers, which were made by spray pyrolysis deposition at different temperatures. The analyses of this study indicate that the efficiency of inverted PSC increases with the Scherrer crystallite size of NiOx. We also observed that the band state of the NiOx layer was changed by Na+ ions migrated from the glass substrate, which also had an impact on the efficiency. The results clearly showed that under high fabrication temperature, migration of matter from the substrate to the hole transport layer affects the electronic structure. Therefore, how these materials are engineered will be important to increase the efficiency of inverted PSCs.

Electrical and Optical Properties of Fluorine-Doped Tin Oxide Films Fabricated at Different Substrate Rotating Speeds during Ultrasonic Spray Pyrolysis Deposition

Electrical and Optical Properties of Fluorine-Doped Tin Oxide Films Fabricated at Different Substrate Rotating Speeds during Ultrasonic Spray Pyrolysis Deposition

Hierarchically Structured 3D Nanoporous Vanadium Oxide Transparent Electrodes for Next‐Generation Supercapacitors

AbstractThis article describes the automatic spray pyrolysis deposition (ASPD) process for the synthesis of hierarchically structured 3D nanoporous vanadium oxide (V2O5) transparent material on a fluorine‐doped tin oxide (FTO) substrate. The deposition of material occurs at 673 K using an aqueous solution of NH4VO3, with a constant solution spray rate of 10 mL min−1 and airflow rate of 10 L min−1. Structural analysis confirms the pure orthorhombic structure formation of the V2O5 material, while FE‐SEM images show a well‐organized 3D spongy‐like porous architecture. The excellent conformality of the ASPD enables the deposition of high‐aspect‐ratio 3D structured nanoporous V2O5 electrodes for next‐generation supercapacitor applications. The hierarchical structured 3D nanoporous V2O5 electrode exhibits superior electrochemical performance in a 1M Na2SO3 electrolyte. Within the potential window 0 to ‐1.3 V, the electrode archives the highest specific capacitance (SC) of 453.32 F g−1 and also retains 86% of its capacitance after 5000 cycles. These properties mainly originate from the crystallinity, 3D nanoporous structure, and fast and easy ionic intercalation through the material. Furthermore, a symmetric supercapacitor device using this electrode is fabricated and which yields outstanding electrochemical performance. Overall, the results highlight the potential of 3D nanoporous V2O5 as an outstanding electrode material for next‐generation supercapacitor applications.

Ultrafast and broadband photodetection based on selenized AgSbS2 thin films prepared by spray pyrolysis deposition and modified with indium nitrate

Broadband AgSbS2(Se) photodetectors are fabricated using spray pyrolysis with a post-selenization process. Indium nitrate is introduced to break the surface blockade to selenidation, largely enhancing the light response range and photocurrent.

Optimisation of the electrochemical performance of (Nd,Gd)1/3Sr2/3CoO3−δ cathode for solid oxide fuel cells via spray-pyrolysis deposition and decoration with Ag nanoparticles

Improved electrochemical performance of (Nd,Gd)1/3Sr2/3CoO3−δ:Ce0.9(Gd,Nd)0.1O1.95 air electrode for SOFCs employing spray pyrolysis deposition and simultaneous decoration with Ag nanoparticles.

Enhancing the Electrochemical Performance in Symmetrical Solid Oxide Cells through Nanoengineered Redox-Stable Electrodes with Exsolved Nanoparticles.

Symmetrical solid oxide cells (SSOCs) have recently gained significant attention for their potential in energy conversion due to their simplified cell configuration, cost-effectiveness, and excellent reversibility. However, previous research efforts have mainly focused on improving the electrode performance of perovskite-type electrodes through different doping strategies, neglecting microstructural optimization. This work presents novel approaches for the nanostructural tailoring of (La0.8Sr0.2)0.95Fe1-xTixO3-δ (LSFTx, x = 0.2 and 0.4) electrodes using a single-step spray-pyrolysis deposition process. By incorporating these electrodes into a Ce0.9Gd0.1O1.95 (CGO) porous backbone or employing a nanocomposite architecture with nanoscale particle size, we achieved significant improvements in the polarization resistance (Rp) compared with traditional screen-printed electrodes. To further boost the fuel oxidation performance, a Ni-doping strategy, coupled with meticulous microstructural optimization, was implemented. The exsolution of Ni nanoparticles under reducing conditions resulted in remarkable Rp values as low as 0.34 and 0.11 Ω cm2 in air and wet H2 at 700 °C, respectively. Moreover, an electrolyte-supported cell with symmetrical electrodes demonstrated a stable maximum power density of 617 mW cm-2 at 800 °C. These findings highlight the importance of combining electrode composition optimization with advanced morphology control in the design of highly efficient and durable SSOCs.

Atomic Layer Deposition of NiO Using Different Precursors with Different Oxygen Sources

NiO thin films have attracted tremendous attention owing to their outstanding chemical stability, good magnetic and catalytic properties1. It is also considered an efficient electrocatalyst for water oxidation, and is one of the few p-type semiconductive oxides with optical transparency due to its wide bandgap of 3.6 eV. Furthermore, NiO films can control high and low conductive states under an external electric field, which is very useful for developing resistance-switching random-access memory devices2.NiO films have been prepared by different deposition techniques, including sputtering, sol-gel, pulsed laser deposition, spray pyrolysis, and chemical vapor deposition (CVD), atomic layer deposition (ALD). Among these, ALD is a powerful technique to grow thin conformal films with fine-tuning of both composition and thickness. The commonly used nickel precursors for ALD process are Ni(Cp)2, Ni(MeCp)2, Ni(EtCp)2, Ni(dmamp)2, Ni(dmamb)2, Ni(acac)2, Ni(apo)2, Ni(dmg)2, Ni(thd)2, and Ni(amd)2 in combination with ozone, water, hydrogen peroxide, or oxygen plasma1. However, ALD of NiO is not well developed yet. The major disadvantages associated with these nickel precursors are low volatility, thermal instability, and poor reactivity or narrow ALD window. Some of these precursors are expensive or very difficult to synthesize. The aforementioned situations indicate that developing a new ALD process for the NiO film with new precursors is pertinent.In this work, we explored different Ni-precursors such as Ni ketoiminates, Ni(ipki)2 and Ni(eeki)2 (their synthesis has been proposed earlier3), and Alanis, provided by Air Liquide. These different reactants combined with different oxygen sources (H2O and O3) resulted in high-quality NiO thin films. Surface analyses indicate NiO films are stoichiometric. They are uniform and exhibit a columnar morphology as determined by TEM (Fig.1a). From the growth characteristics, it is found that the Ni precursors have a strong effect on the GPC. Similarly, the oxygen source affects GPC but it also influences the morphology of the layer leading to significant roughness variations (observed by XRR and AFM). The use of H2O can also result in a nucleation delay. Polycrystalline films are observed when the reaction temperature reaches 125°C, and the crystallinity is further enhanced with deposition temperature (Fig.1b). After comprehensive optimization of the ALD process with Alanis precursor, it has been possible to reach one of the highest growth rate of 1.5 Å/cy, which is nearly seven times higher than that obtained with Ni(EtCp)2 based reaction with the same ALD reactor and having a wide temperature window (100 to 175 °C) with ozone. The same precursor also reacted well with water, giving a GPC of 0.9 Å with an initial nucleation delay. With the use of Ni-ketoiminates, the growth rate could be enhanced considerably with a GPC of 0.7 Å in combination with O3 at a higher temperature.The NiO layers were subsequently used as catalysts for water photooxidation in alkaline medium. The electrochemical properties are better when compared to layers grown by PVD. References Y. Zhang, L. Du, X. Liu, and Y. Ding, A high growth rate atomic layer deposition process for nickel oxide film preparation using a combination of nickel (II) diketonate-diamine and ozone, App. Surf. Sci., 2019, 481, 138-143.H.L. Lu, G. Scarel, X.L. Li, M. Fanciulli, Thin MnO and NiO films grown using atomic layer deposition from ethylcyclopentadienyl type of precursors, J. Cryst. Growth, 2008, 310, 5464-5468.3. D. Zywitzki, D.H. Taffa, L. Lamkowski, M. Winter, D. Rogalla, M. Wark, and A. Devi, Tuning coordination geometry of nickel ketoiminates and its influence on thermal characteristics for chemical vapour deposition of nanostructured NiO electrocatalysts, Inorg. Chem., 2020,59, 14, 10059-10070. Figure 1

Structural and optical properties of cadmium selenide thin film growth with different substrate temperatures by spray pyrolysis deposition

In this work, cadmium selenide (CdSe) thin films were deposited successfully by spray pyrolysis at different substrate temperatures. The influence of the preparation technique on the optical, morphological, and structural properties of the different substrate temperature CdSe films were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Visible optical transmission. The XRD analysis reveals that CdSe thin film has hexagonal (wurtzite) and (cubic) crystal structures with different particle sizes depending on the substrate temperature. The SEM image shows uniform and adherent crystals. The optical energy gap was found to be in the range of 1. 70 – 2.59 eV with different temperatures.

Effect of chromium doping on the band gap tuning of titanium dioxide thin films for solar cell applications

A simple and inexpensive spray pyrolysis deposition (SPD) approach was used to produce TiO2 and Cr (2–8) at.%-doped TiO2 thin films. To explore the morphological features of the films, FE-SEM micrographs were used and found that 6 and 8 at.% TiO2:Cr films had fibrous patterns with diameters of 0.45 and 0.78 μm, respectively, while the remainder of the films were agglomerated particles. From X-ray diffraction investigation, it was found that the TiO2 thin films had an anatase crystal phase (tetragonal) up to 6 at.% Cr doping, while an anatase-rutile mixed crystalline phase was identified for 8 at.% Cr doping. The crystallite size of the pristine TiO2 film was 35 nm, while for TiO2:Cr films, it ranges from 35 to 46 nm. The Fizeau fringes technique was employed to measure the thickness of the TiO2 film and 165 nm was found for pristine TiO2 and 164–180 nm for TiO2:Cr films. UV–visible spectroscopy was used to study optical properties such as absorbance, refractive index, optical band gap, dielectric constant, and optical conductivity. As the Cr concentration increases, the optical band gap decreases from 3.40 eV to 2.70 eV. Using the four-point probe method, it was found that the resistivity changes with temperature and is also affected by the Cr content.

Facile fabrication of thermochromic VO2 (M) films on TiO2-buffered soda–lime glass via a one-step photo-assisted spray pyrolysis route

VO2(M) films have been considered as promising thermochromic coatings for application in smart windows. Meanwhile, the comprehensive performance of the films required for practical smart windows and their large-scale preparation are still great challenges. In this study, a one-step ultraviolet (UV) photo-assisted spray pyrolysis route was developed to prepare thermochromic VO2(M) films on TiO2-buffered soda–lime glass substrates based on molecular dynamicsimulations and related experiments. According to the results, both the luminous transmittance and solar modulation efficiency of the film deposited at 450 °C and exposed to UV photo-irradiation increased by 17% and 40%, respectively, as compared to those of the non-irradiated films. In the case of VO2 and TiO2 single layers as well as bilayer VO2/TiO2 films deposited on substrates preheated to 350 °C-550 °C, it was found that UV irradiation could promote crystallization along with regulating the phase structure, orientation, and morphology, which enhanced thermochromic performance of the photo-treated films. Therefore, photo-assisted spray pyrolysis deposition is a facile, cost-effective and scalable technology for improving the comprehensive performance of as-obtained materials, which is appealing in the large-scale preparation of VO2 smart windows.

Effect of Nickel doping on the Structural, Optical, and electrical properties of titanium dioxide thin films for the application of sensing devices

Thin films of pristine titanium dioxide (TiO2) and doped with different concentrations (0–8) at.% of nickel (Ni) were synthesized onto transparent glass substrates using the spray pyrolysis deposition technique. Field emission scanning electron microscopy revealed the porous and agglomerated surface morphology of the films. X-ray diffractometer demonstrated the anatase crystal structure with a nominal increment of (101) peak. The shifting of peak position revealed the expansion of the unit cell volume from 134.64 to 137.54 (Å)3 whereas crystallite size increased from 34 to 63 nm. Using the Fizeau fringes technique, the thickness of the films was determined between 165 and 190 nm. UV–Vis measurements were employed to examine the optical characteristics of the films. The red shift was observed for 2 at.% Ni content (3.38 eV) while the blue shift was observed for (4–8) at.% Ni content. The wavelength-dependent refractive index and dielectric constant showed anomalous dispersion in the absorption band, representing the transparency of the films. The 4-point probe measurement showed a decreasing trend of resistivity with increasing temperature, whereas the resistivity increased with Ni content. Activation energy indicated a higher amount of adsorbed oxygen in the films due to the high amount of Ni content.

Enhanced dopant incorporation into SnO2 thin films based on dual source spray pyrolysis deposition process

Recently, SnO2 has attracted much attention for optoelectronic applications in infrared (IR) spectral ranges due to its high transparency in the ultraviolet to IR wavelength spectral range and high electrical conductivity. The transition metal-doped SnO2 based on the ultrasonic-assisted spray pyrolysis deposition (SPD) method has been widely used for various optoelectronic applications. However, the SPD process has suffered from inefficient doping of foreign elements due to difficulties in controlling the single precursor source solutions and complicated solution dynamics. To overcome these problems, the co-SPD process supplying the host and dopant solutions separately was suggested for the deposition of the Zn-doped SnO2 thin films. The Zn-doped SnO2 thin films deposited by co-SPD showed insulating electrical properties due to the efficient incorporation of the Zn element as an oxygen vacancy scavenger and acceptor to annihilate the free charge carriers. Also, the Zn-doped SnO2 films showed an IR transmittance of over 80 %, maintained at a temperature of up to 500 ℃. Thus, the co-SPD process can be a promising approach to achieve highly doped oxide films with high IR transmittance even at elevated temperatures.