Chemical Bath Deposited Antimony Oxide Thin Films for Efficient Perovskite Solar Cells.

The metal oxide electron transport layers (ETLs) of n-i-p perovskite solar cells (PSCs) are dominated by TiO2 and SnO2, while the efficacy of the other metal oxide ETLs still lags far behind. Herein, an emerging, economical, and environmentally friendly metal oxide, antimony oxide (Sb2Ox, x = 2.17), prepared by chemical bath deposition is reported as an alternative ETL for PSCs. The deposited Sb2Ox film is amorphous and very thin (∼10 nm) but conformal on rough fluorine-doped tin oxide substrates, showing matched energy levels, efficient electron extraction, and then reduced nonradiative recombination in PSCs. The champion PSC based on the Sb2Ox ETL delivers an impressive power conversion efficiency of 24.7% under one sun illumination, which represents the state-of-the-art performance of all metal oxide ETL-based PSCs. Additionally, the Sb2Ox-based devices show improved operational and thermal stability compared to their SnO2-based counterparts. Armed with these findings, we believe this work offers an optional ETL for perovskites-based optoelectronic devices.

Enhancing the Efficiency and Stability of Perovskite Solar Cells Using Chemical Bath Deposition of SnO2 Electron Transport Layers and 3D/2D Heterojunctions.

Chemical bath deposition (CBD) is an effective technique used to produce high-quality SnO2 electron transport layers (ETLs) employed in perovskite solar cells (PSCs). By optimizing the CBD process, high-quality SnO2 films are obtained with minimal oxygen vacancies and close energy level alignment with the perovskite layer. In addition, the 3D perovskite layers are passivated with n-butylammonium iodide (BAI), iso-pentylammonium iodide (PNAI), or 2-methoxyethylammonium iodide (MOAI) to form 3D/2D heterojunctions, resulting in defect passivation, suppressing ion migration and improving charge carrier extraction. As a result of these heterojunctions, the power conversion efficiency (PCE) of the PSCs increased from 21.39% for the reference device to 23.70% for the device containing the MOAI-passivated film. The 2D perovskite layer also provides a hydrophobic barrier, thus enhancing stability to humidity. Notably, the PNAI-based device exhibited remarkable stability, retaining approximately 95% of its initial efficiency after undergoing 1000-h testing in an N2 environment at room temperature.

Crystalline CdS/Amorphous Cd(OH)2 Composite for Electrochemical CO2 Reduction to CO in a Wide Potential Window.

Electrochemical CO2 reduction is a promising method for converting atmospheric CO2 into valuable low-carbon chemicals. In this study, a crystalline cadmium sulfide/amorphous cadmium hydroxide composite was successfully deposited on the carbon paper substrate surface by in-situ chemical bath deposition (named as c-CdS/a-Cd(OH)2/CP electrodes) for the efficient electrochemical CO2 reduction to produce CO. The c-CdS/a-Cd(OH)2/CP electrode exhibited high CO Faradaic efficiencies (>90 %) under a wide potential window of 1.0 V, with the highest value reaching ~100 % at the applied potential ranging from -2.16 V to -2.46 V vs. ferrocene/ferrocenium (Fc/Fc+), superior to the crystalline counterpart c-CdS/CP and c-CdS/c-Cd(OH)2@CP electrodes. Meanwhile, the CO partial current density reached up to 154.7 mA cm-2 at -2.76 V vs. Fc/Fc+ on the c-CdS/a-Cd(OH)2/CP electrode. The excellent performance of this electrode was mainly ascribed to its special three-dimensional structure and the introduction of a-Cd(OH)2. These structures could provide more active sites, accelerate the charge transfer, and enhance adsorption of *COOH intermediates, thereby improving the CO selectivity. Moreover, the electrolytes consisting of 1-butyl-3-methylimidazolium tetrafluoroborate and acetonitrile also enhanced the reaction kinetics of electrochemical CO2 reduction to CO.

Wetting behavior of stainless-steel surface with zinc oxide nanorod coatings: modulations in nanorod alignment through atomic layer deposition.

This study investigated the hydrophobic-hydrophilic characteristics of zinc oxide (ZnO) nanorod coatings for potential biomedical applications. We examined the effects of different alignments of ZnO nanorods on the wetting and mechanical characteristics of the coatings. ZnO seed layers were prepared on stainless-steel plates using atomic layer deposition (ALD) at five different temperatures ranging from 50 to 250 °C. The ZnO nanorod coatings were then deposited on these seed layers through chemical bath deposition. The polycrystalline structure of the seed layers and the morphology of the nanorods were analyzed using grazing incidence angle x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Mechanical and wetting properties of the nanorod coatings were examined using nanoindentation and water-droplet tests. The seed layers produced at 50 and 250 °C showed stronger (0 0 2) peaks than the other layers. ZnO nanorods on these seed layers exhibited greater vertical orientation and lower water contact angles indicating a more hydrophilic surface. Additionally, vertically oriented nanorod coatings demonstrated greater elastic modulus and hardness than those of oblique nanorods. Our findings indicate that ALD technology can be used to control the spatial arrangement of ZnO nanorods and optimize the hydrophobic-hydrophilic and mechanical properties of coating surfaces.

Chemical bath deposition of SnO2films on PEN/ITO substrates for efficient flexible perovskite solar cells.

Flexible perovskite solar cells (f-PSCs) have achieved significant success. However, high-quality tin dioxide (SnO2) electron transport layers (ETLs) fabricated via chemical bath deposition (CBD) have not been achieved on flexible PEN/ITO substrates. This limitation is primarily due to the corrosion of the poor-quality ITO layer by the strongly acidic CBD solution. Here, we analyzed the reasons for the poor corrosion resistance of ITO films on PEN substrate from multiple perspectives, such as element composition, microstructure, and crystallinity. Then, we proposed a modified CBD method for SnO2films suitable for flexible PEN/ITO substrates. We employed SnCl2·2H2O as the tin source and regulated the pH of the CBD solution by NH3·H2O, which effectively avoided the corrosion of the ITO layer by the CBD solution and achieved high-quality SnO2films on the ITO layers. Compared to the commercial SnO2dispersion, the SnO2films prepared by this method have smaller grains and higher transmittance. As a result, we achieved an unprecedented power conversion efficiency (PCE) of 20.71% for f-PSCs fabricated on PEN/ITO substrates with SnO2ETLs by CBD method. This breakthrough facilitates the development of high-performance f-PSCs by a low-cost and large-scale chemical bath deposition of high-quality ETLs on flexible substrates.

Low-Temperature Chemical Bath Deposition of Conformal and Compact NiOX for Scalable and Efficient Perovskite Solar Modules.

A scalable and low-cost deposition of high-quality charge transport layers and photoactive perovskite layers are the grand challenges for large-area and efficient perovskite solar modules and tandem cells. An inverted structure with an inorganic hole transport layer is expected for long-term stability. Among various hole transport materials, nickel oxide has been investigated for highly efficient and stable perovskite solar cells. However, the reported deposition methods are either difficult for large-scale conformal deposition or require a high vacuum process. Chemical bath deposition is supposed to realize a uniform, conformal, and scalable coating by a solution process. However, the conventional chemical bath deposition requires a high annealing temperature of over 400 °C. In this work, an amino-alcohol ligand-based controllable release and deposition of NiOX using chemical bath deposition with a low calcining temperature of 270 °C is developed. The uniform and conformal in-situ growth precursive films can be adjusted by tuning the ligand structure. The inverted structured perovskite solar cells and large-area solar modules reached a champion PCE of 22.03% and 19.03%, respectively. This study paves an efficient, low-temperature, and scalable chemical bath deposition route for large-area NiOX thin films for the scalable fabrication of highly efficient perovskite solar modules.

High-Throughput Deposition of Recyclable SnO2 Electrodes toward Efficient Perovskite Solar Cells.

Chemical bath deposited (CBD) SnO2 is one of the most prevailing electron transport layers for realizing high-efficiency perovskite solar cells (PSCs) so far. However, the state-of-the-art CBD SnO2 process is time-consuming, contradictory to its prospect in industrialization. Herein, a simplified yet efficient method is developed for the fast deposition of SnO2 electrodes by incorporating a concentrated Sn source stabilized by the ethanol ligand with antimony (Sb) doping. The higher concentration of Sn source promotes the deposition rate, and Sb doping improves the hole-blocking capability of the CBD SnO2 layer so that its target thickness can be reduced to further save the deposition time. As a result, the deposition time can be appreciably reduced from 3-4 h to only 5 min while maintaining 95% of the maximum efficiency, indicating the power of the method toward high-throughput production of efficient PSCs. Additionally, the CBD SnO2 substrates are recyclable after removing the upper layers of complete PSCs, and the refurbished PSCs can maintain ≈98% of their initial efficiency after three recycling-and-fabrication processes.

Fabrication of Well-Aligned ZnO Nanorods with Different Reaction Times by Chemical Bath Deposition Method Applying for Photocatalysis Application.

Zinc oxide nanorods were grown on an aluminum-doped zinc oxide seeds layer using the chemical bath deposition method. The effects of growth reaction time on the structural, optical, and photocatalytic properties of zinc oxide nanorods were investigated. It was clearly observed that the growth direction of zinc oxide nanorods were dependent on the crystallinity of the as-deposited aluminum-doped zinc oxide seed layer. The crystallinity of the obtained zinc oxide nanorods was improved with the increase in reaction times during the chemical bath deposition process. The mechanism of zinc oxide nanorod growth revealed that the growth rate of nanorods was influenced by the reaction times. With increasing reaction times, there were much more formed zinc oxide crystalline stacked growth along the c-axis orientation resulting in an increase in the length of nanorods. The longest nanorods and the high crystallinity were obtained from the zinc oxide nanorods grown within 5 h. The optical transmittance of all zinc oxide nanorods was greater than 70% in the visible region. Zinc oxide nanorods grown for 5 h showed the highest degradation efficiency of methyl red under ultraviolet light and had a high first-order degradation rate of 0.0051 min-1. The photocatalytic mechanism was revealed as well.

Effect of Chemical Bath Deposition Variables on the Properties of Zinc Sulfide Thin Films: A Review.

Zinc sulfide (ZnS) thin films prepared using the chemical bath deposition (CBD) method have demonstrated great viability in various uses, encompassing photonics, field emission devices, field emitters, sensors, electroluminescence devices, optoelectronic devices, and are crucial as buffer layers of solar cells. These semiconducting thin films for industrial and research applications are popular among researchers. CBD appears attractive due to its simplicity, cost-effectiveness, low energy consumption, low-temperature compatibility, and superior uniformity for large-area deposition. However, numerous parameters influence the CBD mechanism and the quality of the thin films. This study offers a comprehensive review of the impact of various parameters that can affect different properties of ZnS films grown on CBD. This paper provides an extensive review of the film growth and structural and optical properties of ZnS thin films influenced by various parameters, which include complexing agents, the concentration ratio of the reactants, stirring speed, humidity, deposition temperature, deposition time, pH value, precursor types, and annealing temperature environments. Various studies screened the key influences on the CBD parameters concerning the quality of the resulting films. This work will motivate researchers to provide additional insight into the preparation of ZnS thin films using CBD to optimize this deposition method to its fullest potential.

Low-Cost Hydroxyacid Potassium Synergists as an Efficient In Situ Defect Passivator for High Performance Tin-Oxide-Based Perovskite Solar Cells.

Perovskite solar cells (PSCs) based on SnO2 electron transport layers have attracted extensive research due to their compelling photovoltaic performance. Herein, we presented an in situ passivation of SnO2 with low-cost hydroxyacid potassium synergist during deposition to optimize the interface carrier extraction and transport for high power conversion efficiency (PCE) and stabilities of PSCs. The orbital overlap of the carboxyl oxygen with the Sn atom alongwith the homogenous nano-particle deposition effectively suppresses the interfacial defects and releases the internal residual strains in the perovskite. Accordingly, a PCE of 24.91 % with a fill factor (FF) up to 0.852 is obtained for in situ passivated devices, which is one of the highest values for SnO2 -based PSCs. Moreover, the unencapsulated device maintained 80 % of its initial PCE at 80 °C over 600 h, 100 % PCE at ambient conditions for 1300 h, and 98 % after one week maximum power point tracking (MPPT) under continuous AM1.5G illumination.

Optimization of ZnO Nanorods Growth on Polyetheresulfone Electrospun Mats to Promote Antibacterial Properties.

Zinc oxide (ZnO) nanorods grown by chemical bath deposition (CBD) on the surface of polyetheresulfone (PES) electrospun fibers confer antimicrobial properties to the obtained hybrid inorganic-polymeric PES/ZnO mats. In particular, a decrement of bacteria colony forming units (CFU) is observed for both negative (Escherichia coli) and positive (Staphylococcus aureus and Staphylococcus epidermidis) Grams. Since antimicrobial action is strictly related to the quantity of ZnO present on surface, a CBD process optimization is performed to achieve the best results in terms of coverage uniformity and reproducibility. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) provide morphological and compositional analysis of PES/ZnO mats while thermogravimetric analysis (TGA) is useful to assess the best process conditions to guarantee the higher amount of ZnO with respect to PES scaffold. Biocidal action is associated to Zn2+ ion leaching in solution, easily indicated by UV-Vis measurement of metallation of free porphyrin layers deposited on glass.

Photoluminescence Study of Ammonium-Free Chemical Bath Deposition of CdS Nanoparticles on Polyester Substrate.

Self-assembled cadmium sulfide (CdS) thin solid films were synthesized by chemical bath deposition (CBD) technique for different deposition times (20 min.­24 h) on transparent and flexible polyester substrates using sodium acetate complex agent. CBD-CdS films were also deposited on glass (BK7) and quartz substrates, as reference. CBD-CdS films on polyester substrate showed a homogeneous deposition, reduction of chemical or structural defects (green emission), and large photoluminescence efficiency in comparison of CBD-CdS films deposited on Si-based substrates. Simulation of PL temperature dependence for polyester CdS films using the rate equation for the carrier population showed the presence of two decay pathways due to cadmium and sulphide defects at crystallite.

Chemical Bath Deposition of p-Type Transparent, Highly Conducting (CuS)x:(ZnS)1-x Nanocomposite Thin Films and Fabrication of Si Heterojunction Solar Cells.

P-type transparent conducting films of nanocrystalline (CuS)x:(ZnS)1-x were synthesized by facile and low-cost chemical bath deposition. Wide angle X-ray scattering (WAXS) and high resolution transmission electron microscopy (HRTEM) were used to evaluate the nanocomposite structure, which consists of sub-5 nm crystallites of sphalerite ZnS and covellite CuS. Film transparency can be controlled by tuning the size of the nanocrystallites, which is achieved by adjusting the concentration of the complexing agent during growth; optimal films have optical transmission above 70% in the visible range of the spectrum. The hole conductivity increases with the fraction of the covellite phase and can be as high as 1000 S cm(-1), which is higher than most reported p-type transparent materials and approaches that of n-type transparent materials such as indium tin oxide (ITO) and aluminum doped zinc oxide (AZO) synthesized at a similar temperature. Heterojunction p-(CuS)x:(ZnS)1-x/n-Si solar cells were fabricated with the nanocomposite film serving as a hole-selective contact. Under 1 sun illumination, an open circuit voltage of 535 mV was observed. This value compares favorably to other emerging heterojunction Si solar cells which use a low temperature process to fabricate the contact, such as single-walled carbon nanotube/Si (370-530 mV) and graphene/Si (360-552 mV).

Chemical-Bath-Deposited Indium Oxide Microcubes for Solar Water Splitting.

We fabricated films of cubic indium oxide (In2O3) by chemical bath deposition (CBD) for solar water splitting. The fabricated films were characterized by X-ray diffraction analysis, Raman scattering, X-ray photoelectron spectroscopy, and scanning electron microscopy, and the three-dimensional microstructure of the In2O3 cubes was elucidated. The CBD deposition time was varied, to study its effect on the growth of the In2O3 microcubes. The optimal deposition time was determined to be 24 h, and the corresponding film exhibited a photocurrent density of 0.55 mA cm(-2). Finally, the film stability was tested by illuminating the films with light from an AM 1.5 filter with an intensity of 100 mW cm(-2).

Direct growth of cobalt hydroxide rods on nickel foam and its application for energy storage.

The present work reports synthesis of cobalt hydroxide (Co(OH)2) rods on nickel foam and its supercapacitor application. Hierarchical Co(OH)2 rods with length of approximately 3.5 µm and diameter of approximately 400 nm were prepared by one-step, simple, and inexpensive chemical-bath-deposition method. The direct growth of Co(OH)2 rods on the Ni foam gave three dimensional (3D) structure for easy access of electrolyte throughout material surface. Also, well-adhered interface between Co(OH)2 rods and Ni-foam surface gave better conduction channels. Detailed electrochemical study was performed by using cyclic voltammetry and galvanostatic charge/discharge measurements. The results demonstrate that Co(OH)2 rods on Ni foam are efficient electrodes for supercapacitor application.

Tunable Hydrogen-Related Defects in ZnO Nanowires Using Oxygen Plasma Treatment by Ion Energy Adjustment.

The chemical bath deposition (CBD) process enables the deposition of ZnO nanowires (NWs) on various substrates with customizable morphology. However, the hydrogen-rich CBD environment introduces numerous hydrogen-related defects, unintentionally doping the ZnO NWs and increasing their electrical conductivity. The oxygen-based plasma treatment can modify the nature and amount of these defects, potentially tailoring the ZnO NW properties for specific applications. This study examines the impact of the average ion energy on the formation of oxygen vacancies (VO) and hydrogen-related defects in ZnO NWs exposed to low-pressure oxygen plasma. Using X-ray photoelectron spectroscopy (XPS), 5 K cathodoluminescence (5K CL), and Raman spectroscopy, a comprehensive understanding of the effect of the oxygen ion energy on the formation of defects and defect complexes was established. A series of associative and dissociative reactions indicated that controlling plasma process parameters, particularly ion energy, is crucial. The XPS data suggested that increasing the ion energy could enhance Fermi level pinning by increasing the amount of VO and favoring the hydroxyl group adsorption, expanding the depletion region of charge carriers. The 5K CL and Raman spectroscopy further demonstrated the potential to adjust the ZnO NW physical properties by varying the oxygen ion energy, affecting various donor- and acceptor-type defect complexes. This study highlights the ability to tune the ZnO NW properties at low temperature by modifying plasma process parameters, offering new possibilities for a wide variety of nanoscale engineering devices fabricated on flexible and/or transparent substrates.

Engineering Mn-Doped CdS Thin Films Through Chemical Bath Deposition for High-Performance Photoelectrochemical Water Splitting.

Doping conventional materials with a second element is an exciting strategy for enhancing catalytic performance via electronic structure modifications. Herein, Mn-doped CdS thin films were successfully synthesized with the aid of the chemical bath deposition (CBD) by varying the pH value (8, 10, and 12) and the surfactant amount (20, 40, 60 mg). Different morphologies like nano-cubes, nanoflakes, nano-worms, and nanosheets were obtained under different deposition conditions. The optimized Mn-doped CdS synthesized at pH=8 exhibited better photoelectrochemical (PEC) performance for oxygen evolution reaction (OER) than pure CdS films, with a maximum photocurrent density of 300 µA/cm2 at an external potential of 0.5 V, under sunlight illumination. The observed performance is attributed to the successful Mn doping, porosity, high surface area, and nanosphere morphology.

Investigation and optimization of In-Vitro behaviour of Perovskite barium titanate as a scaffold and protective coatings.

The piezoelectric effect is widely known to have a significant physiological function in bone development, remodeling, and fracture repair. As a well-known piezoelectric material, barium titanate is particularly appealing as a scaffold layer to improve bone tissue engineering applications. Currently, the chemical bath deposition method is used to prepare green synthesized barium titanate coatings to improve mechanical and biological characteristics. Molarity of the solutions, an essential parameter in chemical synthesis, is changed at room temperature (0.1-1.2 Molar) to prepare coatings. The XRD spectra for as deposited coatings indicate amorphous behavior, while polycrystalline nature of coatings is observed after annealing (300 °C). Coatings prepared with solutions of relatively low molarities, i.e. from 0.1 to 0.8 M, exhibit mixed tetragonal - cubic phases. However, the tetragonal phase of Perovskite barium titanate is observed using solution molarities of 1.0 M and 1.2 M. Relatively high value of transmission, i.e. ∼80%, is observed for the coatings prepared with high molarities. Band gap of annealed coatings varies between 3.47 and 3.70 eV. For 1.2 M sample, the maximum spontaneous polarization (Ps) is 0.327x10-3 (µC/cm2) and the residual polarization (Pr) is 0.072x10-3 (µC/cm2). For 1.2M solution, a high hardness value (1510 HV) is recorded, with a fracture toughness of 28.80 MPam-1/2. Low values of weight loss, after dipping the coatings in simulated body fluid, is observed. The antibacterial activity of BaTiO3 is tested against E. coli and Bacillus subtilis. Drug encapsulation capability is also tested for different time intervals. As a result, CBD-based coatings are a promising nominee for use as scaffold and protective coatings.

Surface topography, structural, optical and dc electrical behaviors of pristine and Co-doped ZnS thin films.

The prime goal of the present research is to synthesize pristine zinc sulfide (PZS) and cobalt (Co)-doped zinc sulfide (CDZS) thin films with different doping concentrations (DC) via chemical bath deposition (CBD) method. The effect of Co-doping on the surface topography, structural, optical and dc-electrical behaviors of PZS thin films has been ascertained. Scanning electron microscopy images exhibited nearly sphere-shaped agglomerates of grains dispersed throughout the surface with cracks in PZS thin film whereas cracks were absent in CDZS. Atomic force microscopy image displayed smooth surface of CDZS thin film with evenly dispersed small grains. The hexagonal wurtzite structure of PZS and CDZS thin films with varied X-ray diffraction (XRD) parameters was confirmed via XRD analysis. Optical investigation revealed that the optical direct band gap energy increased with decreasing DC from 12 % to 4 %. Alteration of other optical parameters namely absorption coefficient, extinction coefficient, refractive index, real and imaginary parts of dielectric constant, etc. with DC was also discussed. Direct current electrical investigation revealed that the current-voltage characteristics are linear for all thin films signifying that the electrical conduction in CDZS is ohmic in nature.

A review on synthesis and applications of gallium oxide materials.

Gallium oxide (Ga2O3), as a new kind of ultra-wide band gap semiconductor material, is widely studied in many fields, such as power electronics, UV - blind photodetectors, solar cells and so on. Owing to the advantages of its excellent performance and broad application prospects in semiconductor technology, Ga2O3 materials have attracted extensive academic and technological attention. This review mainly focuses on introducing the main liquid-phase synthesis methods of Ga2O3 nanoparticles, such as direct-precipitation, chemical bath deposition, hydrothermal, solvothermal, and sol-gel method, including the characteristics in process and advantages and disadvantages of these methods. Then, the effects of reaction conditions, such as pH, capping agent, aging and calcination conditions, on the morphologies and sizes of the precursor and the final products were elucidated. Moreover, the applications of Ga2O3 particles in the fields of catalysis, gas sensors, and other devices in current research on Ga2O3 nanomaterials are discussed with the description of the basic working principle and influence factors.