Papers by Keyword: Spin-Coating

Abstract: Preparing of Sb₂S₃ precursor by sol gel method and the post selenization is a simple and low-cost method for preparing Sb₂(S, Se)₃. In the preparation process of this method, the number of spin-coating of Sb₂S₃ precursor determines the film thickness, structure, and S/Se ratio. In this work, the effects of different spin-coating times (1 to 5) on the structure, optical and electrical properties of the film were studied. The results showed that when the number of spin-coating increased from 1 to 5, the thickness of the film increased from 0.24 μm to 1.17 μm. When spin-coating twice, the strongest diffraction peak of the film changed from (120) to (230); as the spin-coating frequency continued to increase, the film gradually exhibited Sb₂S₃ characteristics, accompanied by a small amount of Sb₂O₃ impurities. In addition, excessive spin-coating cycles can cause large voids to appear on the surface of the film. From the UV-visible spectrum, it can be seen that as the thickness of the film increases, the light absorption also gradually improve, and the band gap increases from 1.34 eV to 1.66 eV. The Mott-Schottky test showed that the prepared thin films were all P-type semiconductor. When spin-coated twice, the carrier concentration of the thin film reached 5.8×10¹⁵cm^-3.

Abstract: In this work we studied the effect of doping on heterogeneous photocatalysis application we used the samples CuO, 5% Ag:CuO, 15% Ag:CuO, 25% Ag:CuO and 50% Ag:CuO catalysts thin layers which were prepared by the sol gel method on a glass substrate. The structural, morphological, optical and electrical characteristics of these layers were studied by XRD, IR, SEM, UV-Vis spectrophotometry and four-point analysis. The results of the XRD, it is observed that the structure of the monoclinic phase develops, with preferential orientations following the plane (-111). This indicated that the thin films are polycrystalline, these results and confirmed by the IR spectra. In the case of Ag doping the SEM revealed the creation of pores on the surface of the samples, which enhanced the degradation of orange II under UV light. The gap energy decreases from 2.17 eV to 1.25 eV with increasing doping. These results show that thin films doped with Ag exhibit a higher degradation than that obtained by pure CuO. After 5 hours in the case of doping with 50% Ag the percentage of degradation is 43%, on the other hand in the pure case the percentage of degradation is 27%.With this, it can be said that 50% Ag:CuO is a good catalyst because the sample has pores, and therefore a larger catalytic area. Creating pores on the surface of the samples, obtaining a less energy gap enables the creation of a greater number of •Oand OH• that works to disintegrate the dye and give the white color to the solution.

Abstract: Photocatalysts that can utilize sunlight energy have attracted attention. In this study, g-C₃N₄ and mesoporous SiO₂@TiO₂ particles were mixed by hydrothermal synthesis. g-C₃N₄ was made by a simple method of directly heating melamine. Mesoporous SiO₂@TiO₂ was prepared using the stover method. These two types of particles were then mixed by hydrothermal synthesis. Hydrothermal synthesis reduced the size of the g-C₃N₄ particles, and they bound more closely with the TiO₂ particles. The degradation of methylene blue dye by visible light was performed to evaluate the organic degradation of the mixed particles. In addition, the mixed particles were formed into a thin film by the spin-coating method. The film's methylene blue degradation performance and the film's power generation performance in a battery were evaluated. The film showed high convenience in the practical application of photocatalytic degradation of organic pollutants because it can be easily separated from the treated liquid after organic matter degradation.

Abstract: Global energy consumption is increasingly becoming high due to industrial activity and advances both in developed and developing countries. Fossil fuels such as coal, natural gas, and oil are used to meet the energy demands all over the world. However, there is a concern about depletion of these resources and rise in greenhouse gas such as carbon dioxide emissions. Therefore, some alternative ways are needed to satisfy the energy demand and decrease the greenhouse emissions. Renewable energy, such as solar energy, wind energy, hydropower, and so on, is a promising source to satisfy the future energy requirements. As to solar cells, there is no need to concern about energy source because it uses solar rays, and it never emits CO₂ when generating electricity.

Abstract: Perovskite CsPbBr₃ has a band gap energy of 2.3 eV which has the potential for solar cell applications. The issue regarding the relationship between the different coating methods and the concentration has not been studied further. Therefore, this study focuses on analyzing the effect of variations in the concentration of CsPbBr₃ 20 mM and 40 mM as well as different coating methods, spin-coating, dip-coating and drop-casting on the morphology of the thin film. The ligand assisted reprecipitation LARP method was used to synthesize CsPbBr₃ using control ligands, octylamine and oleic acid to obtain CsPbBr₃ orthorhombic. Scanning Electron Microscopy (SEM) observations show that increasing the concentration resulted in larger particle size, and the Drop Casting method resulted in a more fully coverage on thin film. Drop Casting and a 40 mM solution produced the highest solar cell efficiency of 1.4 %.

Abstract: Facile synthesis of completely inorganic Zinc oxide-Copper oxide (ZnO-CuO) based bulk heterojunction solar cells (BHJSCs) along with the impact of the film thickness on the different properties like morphological, structural, chemical, optical and electrical have been reported in this work. A simple spin-coating technique was used to fabricate the BHJSC. The elemental presence of ZnO and CuO with wurtzite and cubic phase was confirmed by EDX and XRD analysis correspondingly. The surface quality, optical transmittance and the resistivity of spin-coated BHJ films decrease with increasing the the film thickness revealed by morphological, optical and electrical study respectively. The photovoltaic parameters of FTO/ZnO-CuO/Al heterostructure SC like efficiency η, current density J_sc and fill factor also decreased conspicuously, whereas the open circuit voltage was found to increase conversly. Moreover, experimental outcomes indicate, the thickness of the film has inescapable impact on inorganic BHJSCs performances and must take in consideration during cell fabrication.

Abstract: The surface wettability of thermo-responsive random poly (ethylene glycol methyl ether methacrylate-co-triethylene glycol methyl ether methacrylate), abbreviated as P(MEOMA-co-MEO₃MA), was investigated in thin film. UV-Vis spectroscopy shows that the LCST of P(MEOMA-co-MEO₃MA) with molar ratios of 0:20, 6:14 and 9:11 were 43°C, 32 ^oC and 25 ^oC, respectively. LCST shifts towards lower temperature when molar ratio of MEOMA increases. ATR-FTIR indicates that P(MEOMA-co-MEO₃MA) thin film experienced a collapse when the temperature passes its LCST. The contact angle of the paraffin oil on the film decreases 15^o when the temperature is above its LCST, which confirms the surface wettability can be controlled. Atomic force microscopy shows the surface of the swollen thin film becomes rougher when above it LCST.

Abstract: The main energy losses in solar cells are related to spectral losses where high energy photons are not used efficiently, and energy is lost via thermalization which reduces the solar cell’s overall efficiency. A way to tackle this is to introduce a luminescent down-shifting layer (LDS) to convert these high energy photons into a lower energy bracket helping the solar cell to absorb them and thus generating a greater power output. In this paper, lumogen dye Violet 570 has been used as LDS coated films of 10μm and 60μm placed on top of Si solar cells. The dye was incorporated into polymer films of Polyvinyl Butyral (PVB) and Polymethyl Methacrylate (PMMA) after which they were tested for their absorption, transmission and emission properties. Once optimised layers had been determined, they were deposited directly onto silicon solar cells and the external quantum efficiency (EQE) of the Si solar cells were measured with and without the LDS layers. The resulting graphs have shown an increase of up to 2.9% in the overall EQE efficiency after the lumogen films had been applied.

Abstract: In this work, ZnO thin films were prepared by the low-cost sol-gel deposition method onto six different substrates (glass, ITO coated glass, sapphire (Al₂O₃), p-Si, p-GaN and polyethylene terephthalate (PET)) to study the effects of these substrates on the morphological and structural properties of the produced films. Precursor solution is Zinc acetate dihydrate based dissolved in ethanol with monoethanolamine (C₂H₇NO) added to act as a stabilizing agent to the sol. The corresponding ZnO thin films were characterized using field emission scanning electron microscopy (FESEM), high resolution X-ray diffraction (XRD) and atomic force microscopy (AFM). Results revealed distinct morphological and structural properties of ZnO thin films deposited on each substrate. The most uniform morphology was identified on glass, owing to the acquisition of the averagely stable grain sizes (58 nm – 61 nm) and thin film thicknesses (280 nm – 325 nm). High resolution XRD analysis showed that the films deposited on glass, ITO, p-Si, and p-GaN were attributed to hexagonal crystallite structures while the films deposited on sapphire and PET substrates exhibited amorphous phases. Amongst the samples, the ZnO thin film spin coated on p-Si demonstrated preferred orientation in (002) direction.

Abstract: The observation of random laser (RL) with coherent feedback in transparent polymer films based on Rh6G-PVP by spin-coating was carried out in the present investigation. Some sharp peaks with FWHM identified to be 2 nm appeared on the fluorescent spectra of polymer films which pumped by Nd:YLF pulse laser (wavelength: 526nm, frequence: 1Hz, pulse duration: 1ns, energy power: 1.2mJ/pulse). The threshold of emission spectra is ~35 and the spectra range from 570 ~ 610 nm. Streak camera was used to record the temporal process of RLs and the pulse duration time was measured to ~400ps. Rh6G-PVP transparent films were a kind of polymer films with numerous nanogaps distributed randomly on the surface of the film. The photons will be multiple scatterred and amplified during the spreading in the polymer film owing to the refractive index difference between nanogaps and polymer films. As the Rh6G-PVP polymer films have characters of convenient fabrication processes, low threshold and low cost, it shows great potential application in photoelectron and laser imaging.