مجله مواد و فناوری های پیشرفته
سال دهم شماره 1 (بهار 1400)

 In perovskite solar cells (PSCs), effective electron extraction and reduction of electron-hole pair recombination at the electron transport layer (ETL)/perovskite interface is essential for obtaining higher performance. In this research, the presence effect of a metal oxide ultra-thin layer (< 10 nm thick) on the major ETL (≈ 50 nm thick) in improving the photovoltaic performance of the cell was investigated. For this purpose, a complete set of bilayer structures for the three common ETL metal oxide materials TiO2, SnO2 and WO3, were provided using the accurate and reproducible radio-frequency (RF) sputtering deposition method, and their performance as ETL in the cell was compared. Structural and electrical characterizations of different cells and ETLs were examined by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), UV-vis spectroscopy, Mott-Schottky analysis and J-V diagrams. The use of TiO2/SnO2-UTL, TiO2/WO3-UTL and SnO2/WO3-UTL bilayer structures has been shown to significantly increase cell efficiency by creating more efficient energy band alignment. On the other hand, using their inverted bilayer structures, SnO2/TiO2-UTL, WO3/TiO2-UTL, and WO3/SnO2-UTL, resulted in reduced cell efficiency. The results suggest a simple and promising approach to designe more efficient photovoltaic devices with improved performance.

In this study, the ZSM hierarchical zeolite was prepared and modified by tetraethylenepentamine to be used to remove nitrate ions. The features of synthesized adsorbents were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR)and nitrogen adsorption–desorption isotherms. The results showed that the modified  hierarchical zeolite with the tetraethylenepentamine had a higher adsorption capacity than that of the unmodified hierarchical zeolite in the removal of nitrate ion. The higher adsorption capacity of the amine modified zeolite is due to the presence of amine groups of tetraethylenepentamine, which leads to an increase in the active sites of adsorbent and an electrostatic interaction between the adsorbent surface and nitrate anions. The effect of four parameters including concentration, adsorbent dose, pH and contact time on the nitrate removal using Central composite design approach-based response surface methodology (RSM-CCD) and was investigated and optimized in 22 experiments and 5 levels. Optimal values for a maximum adsorption capacity were 50 milligrams per liter of nitrate, 0.005 g of adsorbent, 25 min and pH = 4.

Doxorubicin (DOX), which is used to treat malignant cancerous tumors, has a high toxicity that by controlling the release of the drug into tumor cells, at the right time and place, the toxicity of the released drug and its side effects can be reduced. In this study, we investigated the release of doxorubicin from SiO2/DOX nanofibers in vitro. Electospun synthesized nanofibers from SiO2/DOX nanoparticles, were used to investigate the release of doxorubicin anticancer drug. X-ray diffraction (XRD) technique showed amorphous structure for nanofibers. According to field emission scanning electron microscopy (FESEM) images, the diameter and approximate length of the synthesized nanofibers were 300-400 nm and several tens of micrometers. Based on the analysis of X-energy diffraction (EDX) spectroscopy, the amount of silicon, oxygen, carbon, nitrogen and chlorine in the samples were: 30.18, 31.84, 29.83, 4.41, and 3.75 percent in the samples, respectively. Xmap analysis showed the homogeneous distribution of silicon, oxygen, carbon, chlorine and nitrogen atoms in nanofibers. Functional species and chemical bonds of nanofibers were detected by FT-IR analysis and showed that silicon has peaks at 1090, 804 cm-1 are related to asymmetric tensile, symmetric tensile vibrations at the Si–O–Si bond. Moreover, vibrations of Si–OH were appeared in the range of 3200 and 3600 cm-1. Drug release to applicant synthesized nanofibers, was investigated in vitro at 37 °C and pH=5.4. As a result, the produced nanofibers have the best and longest release time at pH=5.4 and can be used as drug carriers in targeted treatment anticancer drugs.

In this study, Ni-P-GO nanocomposite coating was applied on the AZ31D surface by the electroless method. After coating, the crystallization process was carried out at 250 °C and 500 °C temperatures for one hour. As a result, microstructural studies by X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that a coating with the semi-amorphous cauliflower morphology formed on the surface. Moreover, after the crystallization process not only the morphology was preserved and the coating colony experienced growth, but also the intermediate phase of nickel phosphide was formed. Therefore, the results showed that as P content increases, the tendency to absorb GO nanoparticles increases. At low temperatures, the Ni2P phase was initially formed. However, as the P content and the crystallization temperature increased Ni2P transformed to Ni3P. As a consequence, this improved the hardness due to both precipitation of the intermediate phases and the crystallization process. As the P increased at 500 °C, the energy needed for forming unstable Ni5p < sub>2 and Ni8p < sub>3 phases was provided. The results of the polarization test showed that applying the coating in comparison with the substrate leads to an increase in corrosion resistance. Besides, increasing P in the field increases the density of the hypophosphite layer which leads to an improvement in corrosion resistance. Corrosion resistance diminished as heat treatment was conducted. Also, as the temperature of the heat treatment increased, 0.424 A/cm2µ passed the surface, which is still lower than 1.328 A/cm2µ, this is specific to the uncoated substrate

In this research, solution based CuInS2 (CIS) thin film solar cell with glass/FTO/TiO2/In2S3/CIS/Carbon structure fabricated from CIS nanoparticle ink. The CIS absorber layer, which is the most important part of the cell, is deposited by drop casting CIS nanoparticle ink dispersed in DMF followed by heat treatment to 250 °C. X-Ray diffraction (XRD) of the absorber layer shows respectable crystallinity with pure chalcopyrite phase. UV-Vis spectrum of the CIS nanoparticle ink confirms high optical absorption in visible wavelengths. Micrographs of the CIS layer show obvious voids and discontinuity in the layer. The discontinuity in the absorber layer has direct impact on the cell performance. In the absence of a packed absorber layer, the charge carriers’ transfer reduces significantly. The absorber layer’s morphology has been improved by controlling the vapor pressure during heat treatment. As a result, the absorber layer changes to a more packed structure with fewer voids. Optimization of the absorber layer deposition leads to and efficiency is enhancement of 136 % from 2.2 % to 5.2 %.

Zinc oxide nanoparticles through precipitation method as a cost-effective and flexible process by two different routes were synthesized. The effect of process parameters on the structure, particle size and antibacterial properties of nanoparticles was investigated by using FESEM, XRD and antibacterial test. FESEM micrographs showed that the nanoparticles synthesized at higher heat treatment temperature without the use of stabilizing agent have particle size within 20-120 nm but those synthesized using stabilizing agent at lower heat treatment temperature have a smaller size in the range of 10-70 nm. In other to incorporate copper into the ZnO structure, the stabilizing agent-containing route was used. The XRD results showed that the use of low concentration of copper led to incorporation of Cu into the ZnO structure. However, two phases of copper oxide and zinc oxide were formed when the higher concentration of copper was used. The antibacterial test against gram-positive bacteria Staphylococcus aureus proved the higher antibacterial activity of the copper doped zinc oxide. The findings indicate that the copper doped zinc oxide nanoparticles may be a good candidate of antibacterial agent for biomedical applications.

Electromagnetic energy converters have been used as electrical energy suppliers. The use of solid magnets in these devices, for producing of magnetic induction, has produced difficulties for the design and application of these systems in various forms and frequencies. Magnetic fluids as a substitute for solid magnets have recently been considered for the use of these devices in low frequency ranges and different designs. In this study, a simple vibrational energy converter was designed using magnetite ferrofluid. For this purpose, the nanoparticles of magnetite were synthesized by co-precipitation method and surface modified by oleic acid. The XRD, FTIR, VSM testes and SEM studies were done to investigate properties of the samples. The nano magnetite particles had the average size of 70 nm and the saturation magnetization of 41.63 emu/gr. Three types of fluid including water, kerosene and brake oil were used to make magnetite stable ferrofluid. The most stable ferrofluid was brake oil based ferrofluid. The fabricated energy converter converted mechanical vibrations to induction voltage and voltage increased with frequency of vibration and applied magnetic field.

The objective of this study was to fabricate and characterize the characteristics of polycaprolactone-sulfonated silk fibroin nanofibrous scaffold for bone tissue engineering applications. Thus, after extraction of silk fibroin (SF) from from Bombyx mori cocoons, silk fibroin (SF) was sulfonated using chlorosulfonic acid and pyridine. Afterwards, a certain amount of sulfonated SF was mixed with polycaprolactone (PCL) solution, and then electrospinning was done using 11 kV high voltage and feeding rate 0.4 mL/h. Various characterization tests were applied to analyze such items such as the structure, chemical composition, bioactivity, cellular attachment, and viability. Fourier transform infrared spectroscopy analyses proved the successful incorporation of sulfate and sulfonate groups in SF structure. The scanning electron microscope shows the formation of continuous and beadless fibers. The average fiber diameter in polycaprolactone nanofibers reduced from 244 nm to 138 nm with the addition of sulfonated SF. Moreover, the water uptake of PCL nanofibers improved from 12.4 % to 167 % after the addition of sulfonated silk fibroin to polycaprolactone. The results of bioactivity and cell culture experiments indicated that sulfonated SF promotes apatitic calcium phosphate deposition and also enhances cellular attachment and viability of PCL nanofibers.