Wet Chemical Deposition Research Articles

PH study of zinc oxide nanorods grown on indium tin oxide coated substrate,

Controlled growth of ZnO nanorods on various substrates is of great interest in photonic and electronic device applications. Also of interest is increasing the optical activity of zinc oxide nanorods in the visible spectrum. In this study, we report pH dependence for the morphology and photoluminescence of aligned ZnO nanorods grown on an indium tin oxide (ITO) coated glass substrate deposited by a wet chemical bath deposition method. The ZnO nanorods were grown by a chemical bath deposition technique using equimolar ratios of zinc (II) nitrate and hexamethylenetetramine in solution at 95 °C. The pH of the reaction solution prior to oven heating was varied from pH 5 to 10.6. Surface properties of the ZnO nanorods on ITO substrates were studied using scanning electron microscopy and photoluminescence spectroscopy. We also compared the use of NaOH to adjust the pH with the use of NH4OH, the latter necessary at higher pH due to the relative insolubility of zinc. It was found that the size of the nanorods can vary twofold with pH and the choice of base. Uniformity of coverage is also significantly dependent upon these variables and will be discussed as it relates to solubility and crystal growth. It was also found that the intensity of the photoluminescence in the visible range is pH dependent. For example, the intensity of luminescence at 550 nm for ZnO nanorods grown at pH 7 using NH4OH is 532% of the corresponding emission for a sample prepared at pH 5.

Synthesis of bioactive β-TCP coatings with tailored physico-chemical properties on zirconia bioceramics.

The objective of this work was to develop a synthesis procedure for the deposition of β-TCP coatings with tailored physico-chemical properties on zirconia bioceramics. The synthesis procedure involved two steps: (i) a rapid wet-chemical deposition of a biomimetic CaP coating and (ii) a subsequent post-deposition processing of the biomimetic CaP coating, which included a heat treatment between 800 and 1200 °C, followed by a short sonication in a water bath. By regulating the heating temperature the topography of the β-TCP coatings could be controlled. The average surface roughness (Ra) ranged from 42 nm for the coating that was heated at 900 °C (TCP-900) to 630 nm for the TCP-1200 coating. Moreover, the heating temperature also affected the dissolution rate of the coatings in a physiological solution, their protein-adsorption capacity and their bioactivity in a simulated body fluid.

Development of Thin Glass-Ceramic Electrolytes Via a Sol-Gel Route

Due to their high energy densitites lithium-air and lithium-sulfur are the most promising battery technologies. Both systems inhibit substantial drawbacks, though. The dendrite formation on the lithium anode and subsequent shorting of the cell is still unsolved since the first market introduction of rechargeable lithium-batteries in the early 1990s. With common liquid electrolytes dendrite formation cannot reliably be prevented. However, solid electrolytes with a high shear modulus effectively inhibit this effect.[1] Solid NASICON-type electrolytes (e. g. Li1+xAlxTi2-x (PO4)3, LATP) offer a high ionic conductivity at room temperature and a high anodic stability. The low stability against metallic lithium, due to the reduction of the transition metal (e. g. Ti4+), requires an intermediary layer.[2] Additionally, a reliable concept for the integration of a free standing and thick (> 50 µm) “electrolyte-sheet” has yet to be proven.In our work, dense electrolyte layers with a thickness below 1 µm were prepared by sol-gel methods (Figure 1). It was intended that a wet chemical deposition of cathode material onto the sintered electrolyte should reduce the interface resistance and that the resistance could be further optimized by varying the deposition and sintering conditions. The electrolyte/electrode interface was analyzed by means of SEM and depth-profiling XPS. Temperature dependent XRD allows for the analysis of the sintering process in situ. The interface resistance was tested galvanostatically and by electrochemical impedance spectroscopy. Electrochemical tests on the electrolyte were performed with sputtered platinum electrodes. The (spectro) electrochemical characterization (Figure 2) of thin-film electrodes on TCO coated glass substrates was realized in specially designed test cells.This poster presents the first results on the sol-gel deposited glass ceramics as electrolyte, thin film cathodes and the interface between both components. Future work will focus on the anode/electrolyte interface (Lithium/polymer/glass-ceramic) and finally a working solid-state cell. [1] W. Xu, J. Wang, F. Ding, X. Chen, E. Nasybulin, Y. Zhang, J.-G. Zhang, Energy Environ. Sci. 2014.[2] P. Knauth, Solid State Ionics 2009, 180, 911–916.

Silver nanostructures formation in porous Si/SiO2 matrix

Self-organized silver nanostructures were grown in porous Si/SiO2 matrix fabricated by ion track technology. The different silver nanostructures with shapes like “sunflowers”, “azalea” or “corn” were realized by applying wet-chemical electroless deposition. We show that reproducible self-organized silver “sunflower” like nanostructures provide a high enhanced Raman signal of Nile blue dye molecules. Signal enhancement for a few or even just a single silver “sunflower” is demonstrated by analyzing the surface-enhanced Raman signature of Nile blue dye molecules. According to this, the silver nanostructures can act as efficient surfaces for surface enhanced Raman spectroscopy as well as (bio)-sensor applications.

Piezotronic Effect on ZnO Nanowire Film Based Temperature Sensor

In this work, we demonstrated the first study of piezotronic effect as a potential means for measuring temperature by utilizing ZnO nanowire (NW) film. The film was synthesized by the wet chemical deposition method and transferred to a flexible substrate using photoresist. The primary role of piezotronic effect over geometrical and piezoresistive effect in the as-fabricated devices has been confirmed, and piezotronic effect on charge carrier transportation under different strains is subsequently studied. In addition, we also presented that the temperature sensing capability of as-fabricated NW film based piezotronic devices can be tuned by piezopotential, which exhibits dramatically enhanced sensitivity. A theoretical model is proposed to interpret the observed behaviors of the sensor. This study provides an effective method to fabricate temperature sensors with higher performance based on piezotronic effect in the future.

Effect of a deposition container on the nanostructural growth and DSSC application of rutile TiO2

Various rutile TiO2 nanostructures were grown using a wet chemical deposition method within plastic, glass, stainless-steel, copper, silver, etc., containers and their application in DSSCs was envisaged for the first time. The reaction rate is different in different containers. The effect of container environment on the morphology and optical properties of rutile TiO2 was investigated and can be attributed to the presence of the respective container element in TiO2. The metals (copper, silver, iron, sodium, etc.) are confirmed (in wt%) in the final products. Due to a change in the morphology followed by absorbance, the power conversion and incident photon-to-electron conversion efficiencies are different (higher in the copper container at 1.97% and 16%, and lower in the stainless-steel container at 0.26% and 3%, respectively). This change in performance can be attributed to a difference in the electron life time values, which are consistent with the charge transfer and series resistance values obtained from Nyquist plots.

Directed Deposition of Nickel Nanoparticles Using Self‐Assembled Organic Template

Self‐assembled organic monolayers are useful templates for nanofabrication. Ordered layer of long alkyl‐chain molecules can direct the wet chemical deposition of metallic coatings on different substrates. Ordered structures of fatty acids and their motions on the phenyloctane/HOPG interface are observed by scanning tunneling microscopy (STM). Modification of self‐assembled fatty acid patterns due to hydroxamic acid presence is also in the focus of the research. Fatty acid layer formation, the structure of the formed thin film on solid/liquid interface, and simultaneous nickel colloidal deposition have been investigated.

High-Quality Transparent Electrodes Spin-Cast from Preformed Antimony-Doped Tin Oxide Nanocrystals for Thin Film Optoelectronics

We present the wet-chemical deposition of antimony-doped tin oxide (ATO) nanocrystals into films and demonstrate that these films have the required high quality to be used as transparent electrodes in thin film optoelectronic devices. Monodisperse, 3 nm diameter ATO nanocrystals, synthesized by an efficient microwave-assisted nonaqueous sol–gel method, are dispersed in tetrahydrofuran (THF) without any additives and processed into films by spin-coating on glass substrates. After thermal treatment, uniform and crack-free films with a low surface roughness of 1.6 nm and tunable thickness of 30 to 800 nm are obtained. A sheet resistance of 395 Ω/square is achieved for a 480 nm thick ATO film with a high transparency of 90% in the visible light range (380–780 nm). To demonstrate that these films are indeed viable as transparent electrodes, we show that an organic light emitting diode (OLED) fabricated on our nanoparticle-based ATO electrode exhibits an electrical and optical performance comparable to an OLED ...

Novel method for the synthesis of a β-tricalcium phosphate coating on a zirconia implant

A novel method for the synthesis of a thin β-tricalcium phosphate (β-TCP) coating on zirconia implants has been developed. The synthesis procedure involves two steps: (i) rapid wet-chemical deposition of a biomimetic CaP coating and (ii) subsequent post-deposition processing of the biomimetic CaP coating, which includes a heat treatment at 900 °C followed by a short sonication in a water bath. The obtained β-TCP coating showed a uniform and dense morphology with a thickness of ≈500 nm and displayed a roughness in the nanometre range (Ra = 28 nm). The β-TCP coating demonstrated an apatite-mineralization ability in a simulated body fluid and enhanced the adsorption of serum proteins on the zirconia. Moreover, the β-TCP coating adhered firmly to the zirconia substrate, developing a notable scratch resistance (Lc = 97 N) and tensile strength (52 MPa) and showed strong resistance towards mechanical forces present during implantation of the coated zirconia implant into the artificial bone.

A chemical deposition method to prepare circular planar 147Pm sources for the measurement of particulate emission in air

This paper describes a method for preparing a circular planar source of 17mm diameter containing approximately 400kBq of 147Pm employing a wet chemical deposition technique to be used in dust monitors. This manuscript described the overall process concept and experimental procedure. The technical feasibility, efficiency of the process and product quality has been evaluated. The quality of the prepared source in terms of nonleachability, uniform distribution of activity and stability, which are necessary attributes of a radioactive source were evaluated and found to be satisfactory.

Sizes and fluorescence of cadmium sulfide quantum dots

Cadmium sulfide quantum dots have been synthesized by wet chemical deposition from an aqueous solution. The sizes of the quantum dots determined by dynamic light scattering directly in the colloidal solution and by intermittent-contact atomic force microscopy in the dry sediment agree with each other. It has been found that splitting of the fluorescence peaks of the quantum dots can be affected by the disorder of the atomic structure of cadmium sulfide quantum dots.

One-step wet chemical deposition of NiO from the electrochemical reduction of nitrates in ionic liquid based electrolytes

Aprotic PYR14TFSI (1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)) ionic liquid served to develop a new electrochemical route for one-step deposition of NiO from PYR14NO3 reduction (1-butyl-1-methylpyrrolidinium nitrate) in a Ni(TFSI)2 (Nickel (II) bis(trifluoromethanesulfonyl)imide) containing electrolyte. The high solubility of the novel PYR14NO3 salt in PYR14TFSI (>0.1M) in comparison with other oxygenated precursors such as oxygen gas, NaNO3 or KNO3 (i.e. 10–15mM) allows the formulation of a broad variety of electrolytes which opens wide possibilities to tune the physico-chemical properties of NiO films (e.g. morphology: from flat to nanostructured films). Furthermore, electrochemical deposition in an electrolyte containing low water concentration (>30ppm by Karl Fisher titration) served to demonstrate that only a small amount of moisture dramatically affects the electrochemical reduction of NO3−, resulting in OH− generation close to the cathode and subsequent NiO(OH)/Ni(OH)2 deposition, as proved by X-ray diffraction and X-ray photoelectron spectroscopy. This finding highlights the importance of aprotic ionic liquids in developing a general electrochemical route for metal oxide deposition without the formation of metal hydroxide species, thus avoiding the requirement for post-deposition annealing treatments. The versatility of the present deposition route as well as its impact in (opto)electronic devices was pointed out by the successful preparation of nanostructured n–p ZnO/NiO heterojunctions exhibiting rectifying current–voltage characteristics.

Wet chemical deposition of single crystalline epitaxial manganite thin films with atomically flat surface

We report the wet chemical deposition of single crystalline epitaxial thin films of the colossal magneto-resistive manganite La0.67Sr0.33MnO3 on the lattice-matched (001)-face of a La0.3Sr0.7Al0.65Ta0.35O3 substrate. Topographic images of these films taken with a scanning tunneling microscope show atomically flat terraces separated by steps of monatomic height. The resistivity of these films shows an insulator-metal transition at 310K, nearly coincident with the Curie temperature of 340K, found from magnetization measurements. The films show a magnetoresistance of 7% at 300K and 1.2T. Their saturation magnetization value at low temperatures is consistent with that of the bulk.

Controllable vertically aligned ZnO nanorods on flexible polyethylene naphthalate (PEN) substrate using chemical bath deposition synthesis

Zinc oxide (ZnO) nanorods were successfully grown on polyethylene naphthalate substrates with a seed layer using a wet chemical bath deposition method at a low temperature. Using various precursor concentrations, the diameter, length, and density of the ZnO nanorods were controlled, and their optical and crystallinity properties were investigated. X-ray diffraction and field emission scanning electron microscopy were used to examine the structure and morphology of the ZnO nanorods. The obtained ZnO nanorods were hexagonal and grew vertically from the substrate in the (002) direction along the c-axis. The low compressive strain values confirmed the high-quality crystal structure of the synthesized ZnO nanorods. A 0.050 M precursor concentration resulted in nanorods with a uniform diameter along their entire length and diameters ranging from 10 nm to 40 nm. The photoluminescence results indicated that the ZnO nanorods grown using a 0.050 M precursor concentration exhibited the sharpest and most intense PL peaks in the UV range compared with the other samples. Therefore, the precursor concentration considerably influenced the growth of the ZnO nanorods. These ZnO nanorods can be greatly applied for the development of flexible, elastic electronic, and optoelectronic devices.

Pr and Cr co-doped BiFeO3nanotubes: an advance multiferroic oxide material

Arrays of single phase pure and Pr-Cr co-doped BiFeO3 (BFO) nanotubes (NTs) with compositions BiFeO3 and Bi0.9 Pr0.1 Fe0.9 Cr0.1 O3 have been synthesized using Anodic Aluminium Oxide (AAO) template (pore diameter ~250 nm) by wet chemical liquid phase deposition technique. All the NTs show ferromagnetic nature at room temperature (RT). Better magnetic properties are observed in the co-doped BFO NTs with the value of saturation magnetization (MS ) ~49 memu/g, magnetization at the remanence (MR ) ~12 memu/g and coercive field (HC ) ~103 Oe. Increase of ferromagnetic signature in the co-doped BFO NTs is believed to be due to the collapse of the space-modulated spin structure. Significant increase in the dielectric characteristics in co-doped BFO NTs suggests lowering of leakage current due to the reduction of the oxygen vacancies in the structure. Strong Magnetodielectric effect (MD), expressed by [e r (H)-e r (0)]/e r (0) is observed in doped BFO NTs, where the increase of the dielectric constant is noticeable with the increase in the applied magnetic field. The codoped BFO NTs show noticeable increase in MD effect at a lower field (1-2 kOe).

High-quality ZnO nanorods grown on graphite substrates by chemical solution method

ZnO nanorods (NRs) were grown perpendicularly on graphite substrates using low-temperature wet chemical bath deposition (CBD) with sputtered ZnO film as seed layer. The individual ZnO NRs exhibit single-crystalline feature with well defined hexagonal prism shape and smooth side facets. The high optical qualities of ZnO NRs on graphite substrates were demonstrated by the dominant near-band edge emission and nearly undetectable deep level emissions in room-temperature photoluminescence spectra. The extremely low average reflectance of 0.45 % was obtained for the ZnO NRs/graphite structure in the spectra range from 200 to 1100 nm, indicating that the reported ZnO NRs/graphite structures have significant opportunity for potential application in high-performance photovoltaic devices. Considering the excellent material characteristics of ZnO NRs and the versatile and fascinating features of graphite substrates, the achievements make it possible for the development of high-performance ZnO-based nano-devices even in transferable, flexible, or stretchable forms.

Surface photovoltage analysis of ZnO nanorods/p-Si heterostructure

In this work, n-type ZnO nanorods (NRs) were fabricated on a p-type Si substrate to form a ZnO NRs/Si structure using a low-temperature wet chemical bath deposition method. Kelvin-probe-based surface photovoltage (KP-based SPV) technology was used to study the behavior of surface photogenerated charges for the as-grown heterostructure. In general, the KP-based SPV response range of the ZnO NRs/Si structure was significantly expanded compared with the bare Si substrate, due to the incorporation of ZnO NRs. Moreover, the SPV response amplitude for ZnO NRs/Si structure also depended on the length and diameter of the NRs, and the corresponding mechanism was elucidated in terms of O2 adsorption. The photovoltaic application of the ZnO NRs/Si based structure would benefit significantly from these achievements.

Vertically aligned ZnO nanorods synthesized using chemical bath deposition method on seed-layer ZnO/polyethylene naphthalate (PEN) substrates

Vertically well-aligned zinc oxide (ZnO) nanorods were successfully grown by using wet chemical bath deposition synthesis on a seed-layer ZnO/polyethylene naphthalate at a low temperature. The strong and sharp (002) peak in the XRD indicated that ZnO nanorods grew vertically in the (002) direction along the z-axis on the substrate and had a high-quality single crystalline structure. The low value of the compressive strain (−0.0153%) revealed that ZnO nanorods preferred to grow along the c-axis. Hexagonal ZnO nanorods with diameters ranging from 10nm to 40nm grew vertically from the substrate and caused the sharp and strong peak in the UV range located at 390nm in the photoluminescence emission spectrum. These ZnO nanorods can be widely used for the development of flexible, optoelectronic, and elastic electronic devices.

UV irradiated wet chemical deposition and characterization of nanostructured tin sulfide thin films

Tin sulfide (Sn2S3) films were synthesized both by chemical bath deposition method without (CBD) and with simultaneous irradiation of UV light (UV–CBD). The influence of UV illumination on the synthesis of Sn2S3 thin films were investigated through the structural, compositional, morphological, optical and electrical studies. CBD films were Sn2S3 having orthorhombic structure with some impurities while that of UV–CBD films exhibit excellent crystallinity of pure single phase Sn2S3 having the same structure. Morphology of CBD films was spherical grains of different sizes while that of UV–CBD films was uniformly distributed thin long nanoworms. Optical properties of the films were different and the optical band gap for CBD and UV–CBD films was 1.20 and 1.57 eV respectively. Refractive index of the films lies in 1.84–2.02 in the 700–1,500 nm wavelength range. Electrical resistivity of the CBD and UV–CBD films was 104 and 103 Ωcm for respectively. UV irradiation during the synthesis of tin sulfide films had highly enhanced the properties demanded by various optoelectronic applications. UV–CBD is a novel, simple and cost effective approach, having the potential to stimulate new research in the study of tin sulfide thin films and other metal chalcogenides.

Synthesis of Nest-Like NiO and its Application on P-Type Dye-Sensitized Solar Cell

The nest-like NiO was successfully prepared by calcining the Ni(OH)2 precursor synthesized using wet chemical deposition method. A NiO-based p-type dye-sensitized solar cell was fabricated. The photocathode films were coated by doctor-blading NiO paste onto the FTO substrates. The thickness of NiO film was controlled by repeatedly blade coating using one layer of tape. The results manifested that the thickness of the NiO film significantly influenced the photoconversion efficiency. The solar cell based on the NiO film with 13 μm thickness showed the highest photoconversion efficiency. In addition, the influence of the dye is also investigated. The NiO films were sensitized with C343, N3, and Z907, respectively. The measurement of photocurrent density-voltage characteristics indicated that the highest photoconversion efficiency is about 0.027% using C343 sensitized.