Precursor Solution Temperature Research Articles

Effect of precursor solution temperature on the morphology and electrochemical performance of electrodeposited MnO2 nanofilms for lithium-ion batteries

ABSTRACT This study investigated the impact of precursor solution temperature on the electrodeposition of MnO2 material, which were prepared on a nickel substrate using the electrodeposition method under varying precursor solution temperatures of 25°C, 40°C, 50°C, and 60°C, respectively. These materials were subsequently employed as anodes in lithium-ion batteries to study their electrochemical performance. The results indicate that an increase in temperature induces preferential aggregation and growth of MnO2 nanosheets towards specific orientations, which is advantageous for enhancing the electrochemical performance of MnO2 electrode materials. Notably, the electrode material prepared at a solution temperature of 50°C exhibited optimal performance. Additionally, the charge transfer impedance was lower, which could be attributed to the growth of the highly conductive β-MnO2 main phase under 50°C. This study presents a novel approach for effectively improving electrodeposited nanomaterials, offering insights into the optimisation of electrochemical performance.

Ppb-level H2S gas sensor based on CuNi-MOFs derivatives for meat freshness detection at low temperature environment

H2S is usually used as one of the landmark gases for meat freshness detection under low temperature storage conditions. In this paper, the NiO-doped CuO composite derived from MOFs was synthesized by a low temperature (−25 ℃) precursor hydrothermal and sintering procedure for H2S detection. The influence of precursor solution temperature and sintering temperature on the structure of MOFs derivatives were discussed by SEM, TEM, and XRD characterization. The hydrothermal method of low-temperature precursor has guiding significance in improving the gas response performance of MOFs/MOFs derivatives. The sensor based on NiO-doped CuO composites derived from MOFs exhibited a ppb-level response to H2S gas. The sensor response is 106 % to 50 ppb H2S. Meanwhile, the sensor has good selectivity, and the response and recovery time are 115 s and 251 s, respectively. The low temperature precursor hydrothermal method directly affected the morphology and structure of MOFs derivatives by regulating the kinetics for MOFs nucleation and crystal growth, obtains more active adsorption sites. In addition, the composite has good sensing performance for H2S at the ambient temperature of 4 ℃ and −18 ℃, which verified the effectiveness for the detection of meat spoilage under a low temperature storage. Furthermore, the sensor based on NiO-doped CuO composites is a good candidate for H2S gas detection in meat freshness evaluation. Finally, an integrated circuit detection system was designed to detect H2S gas at different ambient temperatures. This work provides a new idea for meat freshness detection in a cold storage environment.

Influence of precursor solution temperature on the crystalline nature of mixed halide perovskite thin films grown by one-step deposition method

The influence of the precursor solution temperature (40 °C, 50 °C, 70 °C and 90 °C) on the crystalline nature of the mixed halide methyl ammonium lead iodide perovskite (MAPI) thin films grown using one-step deposition method is investigated. Precursor solution used is a combination of Lead chloride, Lead iodide and Methyl ammonium iodide at a composition of 1:1:4 in Dimethylformamide. Better crystallinity (> 70%) and largest crystallite size (~ 76 nm) are observed in the thin films prepared with solution temperature at 40 °C and 70 °C, respectively. Two different mechanisms that are responsible for better crystallinity and growth of crystallite in the perovskite thin films under study are identified. The observed variation in crystallinity is attributed to the amount of formation of solvent-induced intermediate phase in thin films, as evidenced from the presence of XRD peak at 7.4°. The formation of intermediate phase controls the otherwise fast and uncontrolled crystallization of perovskites to produce better crystalline nature. Variation in the crystallite size is attributed to the nature of the growth of intermediate compound, Methyl ammonium lead chloride, which determines the possibility of template-assisted growth of MAPI. This study emphasizes the critical role of the formation of intermediate phase along with the template-assisted growth in the fabrication of highly crystalline perovskite thin films with large crystallite/grain size that are indispensable for the fabrication of efficient devices.

Photoelectrocatalytic improvement of copper oxide thin film fabricated using anodization strategy application in nitrite degradation and promoting oxygen evolution

This research is to develop Cu oxide thin film preparation using the anodization technique for the highest efficiency nitrite degradation and promoting oxygen evolution improvement. The electrochemical cell is developed by designing the electrode position to enhance the efficiency of Cu oxide thin film deposition on the anode electrode. The effects of precursor solution temperature, deposition time, and calcination temperature were studied to enhance the photoelectrocatalytic water reduction properties. The characteristics of the fabricated Cu oxide thin film were studied using scanning electron microscope, X-ray diffraction, and electrochemical impedance spectroscopy methods related to the photoelectrocatalytic activity improvement. The calcination temperature is a significant factor affecting physical properties, crystalline structure, morphology, and charge transfer rate, which relate to the photoelectrocatalytic activities. We have succeeded in developing the photoelectrocatalytic cell using the developed Cu oxide photocathode in cooperation with the FTO/WO3/BiVO4 photoanode for nitrite degradation and simultaneous oxygen production up to 98% and 6.0 mgO2/L for 120 min, respectively. This research is especially suitable for further development leading to a water treatment application that eliminates inorganic ions and increases the dissolved oxygen value in an aquarium system.

Precursor solution temperature dependence of the optical constants, band gap and Urbach tail in organic–inorganic hybrid halide perovskite films

The band gap energy and optical constants are important parameters for solar cell design. Here, organic–inorganic hybrid halide perovskite CH3NH3PbI3 films (about 140 nm thick) were prepared by vapor deposition at precursor solution temperatures of 30 °C, 50 °C, 70 °C, and 90 °C, respectively. By fitting the ellipsometric spectra in the photon energy range of 0.496–4 eV, we can find that the optical constants, absorption coefficients, and dielectric function strongly depend on the precursor temperature. Due to the change of electronic band structures and spin–orbit coupling, the band gap energy can be modulated from 1.634 eV to 1.516 eV with different precursor temperatures. As band gap energy increases, the Urbach energy decreases with each precursor temperature. The film with a precursor temperature of 70 °C shows the lowest Urbach tail energy (107 meV). The Urbach tail effects can be ascribed to the cumulative effect of impurities, the degree of disorder, and electron–phonon interaction. This study is helpful for understanding the intrinsic optical properties of perovskite films fabricated under different precursor temperatures, so as to provide important information for understanding the device physics and fabrication of high performance perovskite solar cells.

Temperature-assisted crystallization for inorganic CsPbI2Br perovskite solar cells to attain high stabilized efficiency 14.81%

Due to its super thermal stability, inorganic CsPbI2Br perovskite has attracted more and more attention in the field of photovoltaic application. However, its device performance, as reported to date, is greatly challenged in preparing CsPbI2Br films with both sufficient absorbance and high quality. Herein, crystallization engineering is applied in producing solution-processed CsPbI2Br film to guarantee sufficient light harvesting and effective carrier extraction. Further study proves that the precursor solution temperature would largely affect the crystallization progress: (1) the nucleation step is highly related to the solubility of precursor in a specific solvent or solvents at elevated temperatures; (2) the crystal growth rate is highly related to the solvent evaporation rate. To obtain thick film with larger crystalline grain size, the precursor solution temperature should be carefully adjusted for both suppressing the formation of too many nuclei and increasing the crystallization rate at the same time. Finally, the optimized CsPbI2Br would be obtained when the precursor solution is maintained at 100 °C, the corresponding device shows a stabilized efficiency as high as 14.81%. As far as we know, this is the highest PCE for the CsPbBrI2 perovskite based solar cells.

Effects of process variables on aqueous-based AlOx insulators for high-performance solution-processed oxide thin-film transistors

Recently, aqueous method has attracted lots of attention because it enables the solution-processed metal oxide thin film with high electrical properties in low temperature fabrication condition to various flexible devices. Focusing the development of aqueous route, many researchers are only focused on metal oxide materials. However, for expansive application of the aqueous-based metal oxide films, the systematic study of performance change with process variables for the development of aqueous-based metal oxide insulator film is urgently required. Here, we propose importance of process variables to achieve high electrical-performance metal oxide insulator based on the aqueous method. We found that the significant process variables including precursor solution temperature and humidity during the spin-coating process strongly affect chemical, physical, and electrical properties of AlOx insulators. Through the optimization of significant variables in process, an AlOx insulator with a leakage current value approximately 105 times smaller and a breakdown voltage value approximately 2–3 times greater than un-optimized AlOx was realized. Finally, by introducing the optimized AlOx insulators to solution-processed InOx TFTs, we successfully achieved InOx/AlOx TFTs with remarkably high average field-effect mobility of ∼52cm2V−1s−1 and on/off current ratio of 106 at fabrication temperature of 250°C.

Influences of Precursor Solution Concentration and Temperature on CH3NH3PbI3 Perovskite Layer Morphology and the Unconverted PbI2 Proportion to their Perovskite Solar Cell Characteristics

The formation of organometal-halide perovskite crystal is simply based on stoichiometry reaction. However, the formation process seems to be sensitively affected by some process parameters such as concentration and temperature of precursor solution. In this work, we studied the formation of CH3NH3PbI3 (MAPbI3) crystal in mesoporous TiO2 layer deposited by spin coating technique. Perovskite layers were characterized by X-Ray Diffraction (XRD) and its surface morphology were investigated by Scanning Electron Microscope (SEM). Perovskite layers obtained from precursor solution at 40°C and 60°C show a mesh-like structure. Meanwhile, for higher precursor solution temperature (80°C), it shows a flake-like structure. However, precursor solution at 60°C produced the best conversion of precursor solution with the smallest percentage of the remaining unconverted PbI2 inside the produced crystal layer. These experimental results also showed that the best crystallization degree is obtained from 1.0 M precursor solution. The photovoltaic characteristics of their solar cells seem to have a correlation with the quantity of unconverted PbI2. High PbI2 content significantly decreased the Filling Factor of the solar cell.

Impact of perovskite precursor solution temperature on charge carrier dynamics and photovoltaic performance of perovskite based solar cells

Even though perovskite based solar cells have been routinely fabricated with preheated perovskite solutions, currently the underlying mechanism of how the perovskite precursor solution temperature influences perovskite solar cells has not been studied yet. Therefore, we investigated the impacts of perovskite solution temperatures on charge carrier dynamics of perovskite film and perovskite solar cell performance that were quantitatively analyzed using steady-state photoluminescence (PL), time-resolved emission spectra (TRES), excitation-dependence of PL and current-voltage measurements. It is found that the perovskite solution temperature greatly influenced the morphologies, defect densities and states, and charge recombination dynamics of perovskite thin films. Particularly, steady-state and time-resoled PL measurements revealed that perovskite thin films prepared with the perovskite solution temperature around 70 °C produced lowest surface and bulk defect densities. In addition, it is found that the perovskite solution temperature around 70 °C led to exciton-like transitions while lower and higher solution temperatures led to defect-mediated recombination of perovskite thin films. Such recombination dynamics of perovskite films strongly influenced the light absorption and extraction efficiencies of photogenerated charge carriers which in turn influenced short-circuit current, fill factor, and open circuit voltage of perovskite solar cells. As a result, better photovoltaic performance of perovskite solar cells was observed when prepared with the precursor temperature around 70 °C.

Modulation of aqueous precursor solution temperature for the fabrication of high-performance metal oxide thin-film transistors

In this study, we present a simple process for the fabrication of aqueous-solution-processed metal oxide thin-film transistors (TFTs) via the manipulation of precursor solution temperature. Indium oxide TFTs fabricated from a solution of indium nitrate at 4 °C exhibited the highest mobility of 2.73 cm2/(V·s) at an annealing temperature of 200 °C. When the temperature of the metal oxide precursor solution is 4 °C, metal cations within the solution can be fully surrounded by H2O molecules owing to the high dielectric constant of H2O at low temperatures. These metal complexes are advantageous for the conversion of metal oxides via thermally driven hydrolysis and condensation processes due to their high potential energies. The same techniques have been applied successfully with high-order metal oxides including indium zinc oxide, indium gallium oxide, and indium gallium zinc oxide.

Enhanced power conversion efficiency of CdS quantum dot sensitized solar cells with ZnO nanowire arrays as the photoanodes

We report the fabrication of CdS quantum dot sensitized solar cells with ZnO nanowire arrays as the photoanodes. The influences of precursor solution temperature and sensitizing cycles on the performance of CdS quantum dots sensitized ZnO nanowires solar cells were studied. Successive ionic layer adsorption and reaction (SILAR) method was applied to deposit CdS quantum dots on the surface of ZnO nanowire arrays for assembling ZnO/CdS electrodes. The results of scanning electron microscopic (SEM), X-ray diffraction (XRD) patterns and UV–vis absorption spectroscopy indicated that the ZnO nanowires electrodes were well-covered with CdS quantum dots. The temperature of the ethanol sensitizing solutions significantly influenced the performance of ZnO/CdS electrodes by affecting the rate of deposition reaction and the penetration ability of ethanol solution. The CdS quantum dots sensitized ZnO-based solar cells exhibited a short-circuit current density (Jsc) of 3.1mA/cm2, an open-circuit voltage (Voc) of 0.55V and a photovoltaic conversion efficiency of 0.72%, which is much higher than that reported in literatures, under the illumination of one sun (AM 1.5, 100mW/cm2) when the temperature of the ethanol solutions was 60°C and ZnO arrays were sensitized for seven times.

Effect of heat-treatment on the structural and optical properties of Cu2S thin films deposited by CBD method

Semiconducting Cu2S thin films were successfully deposited on glass substrate under three different conditions such as as-deposited, post heat-treated and pre heated precursor solution by chemical bath deposition technique. Structural and optical properties of the films were characterized by X-ray diffraction (XRD), scanning electron microscope, energy dispersive X-ray (EDX) analysis and UV–Visible spectrophotometer. The XRD spectra showed the amorphous nature of thin films with hexagonal structure. The d value and micro strain increased and the average crystallite size decreased from 1.9 to 1.4 and 1.3 nm respectively when the as-deposited film was subjected to post heat-treatment and the precursor solution temperature was elevated. The presence of more nucleation centers and fast reaction rate decreased the average crystallite size in films grown with pre heated precursor solution. The noticed blue shift in energy gap and the shift of XRD peak position towards the lower 2θ side by heat-treatment could be considered as a sign of the quantum confined effect due to the formation of the nano-sized Cu2S crystals on the surface. The transmittance of heat-treated Cu2S films in the visible region matched the phototropic vision of human eye (~600 nm) which makes them suitable for solar control coatings on architectural windows and automobiles in the regions with warm climates. Low transmittance behaviour of pre heated Cu2S films could be used for anti dazzling coatings for car windscreens and driving mirrors to reduce the dazzling effects of light at night. EDX spectra showed the chemical purity of the films. The observed broad absorption and blue shift in band gap of the heat-treated films were due to quantum confinement effect. Fourier transform infrared studies were also carried out and the results are presented.

Effects of Solution Temperature on Solution-Processed High-Performance Metal Oxide Thin-Film Transistors

Herein, we report a novel and easy strategy for fabricating solution-processed metal oxide thin-film transistors by controlling the dielectric constant of H2O through manipulation of the metal precursor solution temperature. As a result, indium zinc oxide (IZO) thin-film transistors (TFTs) fabricated from IZO solution at 4 °C can be operated after annealing at low temperatures (∼250 °C). In contrast, IZO TFTs fabricated from IZO solutions at 25 and 60 °C must be annealed at 275 and 300 °C, respectively. We also found that IZO TFTs fabricated from the IZO precursor solution at 4 °C had the highest mobility of 12.65 cm2/(V s), whereas the IZO TFTs fabricated from IZO precursor solutions at 25 and 60 °C had field-effect mobility of 5.39 and 4.51 cm2/(V s), respectively, after annealing at 350 °C. When the IZO precursor solution is at 4 °C, metal cations such as indium (In3+) and zinc ions (Zn2+) can be fully surrounded by H2O molecules, because of the higher dielectric constant of H2O at lower temperatures. These chemical complexes in the IZO precursor solution at 4 °C are advantageous for thermal hydrolysis and condensation reactions yielding a metal oxide lattice, because of their high potential energies. The IZO TFTs fabricated from the IZO precursor solution at 4 °C had the highest mobility because of the formation of many metal-oxygen-metal (M-O-M) bonds under these conditions. In these bonds, the ns-orbitals of the metal cations overlap each other and form electron conduction pathways. Thus, the formation of a high proportion of M-O-M bonds in the IZO thin films is advantageous for electron conduction, because oxide lattices allow electrons to travel easily through the IZO.

減圧沸騰噴霧熱分解を用いたナノ粒子合成

Abstract An innovative nanosized metal particle synthesis method by flash boiling atomization is proposed. Methane-oxygen premixed flame is utilized as the heat source and the precursor water solution is sprayed into the low-pressure field. Then, droplets are secondary-atomized by flash boiling phe-nomenon. The zinc acetate water solution is used as the precursor to synthesize ZnO nanosized metal particles. From the view point of industrial aspects, the size controlla-bility of nanosized metal particle, the inhibition of agglomeration and the inexpensive large production quantity are required for the particle synthesis method. The synthesis method, which is presented in this paper, is expected to achieve the above-mentioned characteristics. In this paper, firstly, the flashing spray is observed by using Mie scat-tering method. Secondly, ZnO nanosized metal particles are synthesized to investigate the effect of the flash boiling atomization on the synthesized particles. It was found that the droplets were well atomized and dispersed when the flash boiling phenomenon occurred. In addition, the higher the temperature of precursor solution became (above the saturated temperature), the smaller the synthesized particles were.

Comparison of Polythionates as Precursors for the Formation of Thallium Sulfide Layers

The processes of obtaining layers of thallium, sulfides, Tl x S y , by the sorption-diffusion method on polyamide 6 using solutions of lower polythionates - sodium trithionate and tetrathionate, Na 2 S 3 O 6 , Na 2 S 4 O 6 , potassium pentathionate, K 2 S 5 O 6 , and of dodecathionic acid, H 2 S 12 O 6 , as precursors of sulfur are compared. The concentration of sorbed sulfur increases with increasing the duration of treatment, the concentration and temperature of precursor solution. It rather significantly also depends on the nature - sulfurity of polythionate, i. e. on the number of sulfur atoms in the polythionate anion: effectiveness of sulfurization using solutions of dodecathionic acid is significantly higher than that of lower polythionates. Thallium sulfide layers are formed on the surface of polyamide after the treatment of sulfurized polymer with Tl(I) salt solution. The concentration of thallium in the layer increases with the increase of initial sulfurization duration and in case of H 2 S 12 O 6 solution used - on the temperature of this process. The results of X-ray diffraction analysis confirmed the formation of thallium sulfide layers in the surface of polyamide 6. The phase composition of layer changes depending on the conditions of initial treatment in a H 2 S 12 O 6 solution. Five thallium sulfide phases, two forms of TlS, Tl 2 S 2 , Tl 4 S 3 and Tl 2 S 5 were identified in the composition of the layers treated for different time with a solution of dodecathionic acid at the temperature of 20 °C and 30 °C and then with Tl(I) salt solution by X-ray diffraction but the maxima of TlS and Tl 2 S 5 phases predominate in the diffractograms. http://dx.doi.org/10.5755/j01.ms.17.4.774

Formation and study of mixed copper sulfide-copper telluride layers on the surface of polyamide 6

Abstract The layers of mixed copper chalcogenides, CuxS-CuyTe, were formed on the surface of polyamide using solutions of potassium and sodium telluropentathionates, K2TeS4O6 and Na2TeS4O6, respectively, and of telluropentathionic acid, H2TeS4O6, as precursors of chalcogens. The concentration of sorbed chalcogens increased with the increasing time of the treatment, concentration and temperature of precursor solution. CuxS-CuyTe layers are formed on the surface of polyamide after the treatment of chalcogenized polymer with Cu(II/I) salt solution. The concentration of copper in the layer increases with the increase of chalcogenization duration, concentration and the temperature of chalcogenization solution. In the surface of CuxS-CuyTe layers various copper, sulfur, tellurium and oxygen compounds (Cu2S, CuS, S8, CuxS, CuyTe, Cu(OH)2 and TeO2) were present. Chalcogenides were the major components in the layer. Chalcogenide phases — digenite, Cu1.8S, djurleite, Cu1.9375S, anilite, Cu7S4, geerite, CuS2, chalcocite, Cu2S, tetragonal Cu3.18Te2, Cu2.72Te, hexagonal Cu2Te, Cu4Te3, Cu1.80Te, Cu1.85Te2, and orthorhombic vulcanite, CuTe were identified in the layers by X-ray diffraction. Electrical sheet resistance of CuxS-CuyTe layers vary from ∼ 1.0 kW cm−2 to 4×103 kΩ cm−2. It is concluded that the formation of chalcogenide layers proceeds in the form of islands which grow into larger agglomerates. Use of the gathered data enables design and formation of the CuxS-CuyTe layers with desired conductivities.