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Correlation between the morphology and the opto-electronic and electrical properties of organometallic halide perovskite (CH<sub>3</sub>NH<sub>3</sub>MH<sub>3</sub>) thin films
摘要： Organometallic halide perovskites are emerging as a promising class of materials for optoelectronic applications. Crystal morphology is important for improving the organic-inorganic lead halide perovskite semiconductor property in optoelectronic, electrical and photovoltaic devices. It is thus important to investigate how the changes in crystal morphology affect the semiconductor behavior. This work presents a study that was carried out to assess the relationship between different deposition methodologies and the opto-electronic and electrical properties of the resultant organometallic halide perovskite thin films. Herein, single step solution deposition method and two step solution deposition methods have been used to deposit perovskite thin films. The structure and morphology of perovskite was controlled by changing concentration, annealing temperatures and dip coating times. From the study, prepared films showed different morphologies as the concentration, annealing temperatures and dip coating times were varied. Optical band gap energies of 2.23 eV, 2.13 eV and 2.09 eV were obtained for samples prepared by single step solution deposition method and 1.57 eV, 1.55 eV and 1.52 eV for two step solution deposition method. The sheet resistance values decreased with an increase in concentration, annealing temperatures and dip coating times. The decrease in optical band gap energy and sheet resistances are excellent properties for high performance photovoltaic devices.
关键词： Perovskite,sheet resistivity,activation energy,band gap,sheet resistance,spectroscopy
更新于2025-11-19 16:56:35
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Textural and electro-optical study of a room temperature nematic liquid crystal 4ì?-pentyl-4-biphenylcarbonitrile doped with metal oxide nanowires in planar and in-plane switching cell configurations
摘要： This work shows the doping effect of metal oxide nanowires (alumina nanowires) on the textural and electro-optical characteristics of nematic liquid crystal (5CB) in planar and in-plane switching (IPS) cell configurations. Results indicate the increase in nematic to isotropic phase transition temperature after doping in both planar and IPS cells. A decrease in threshold voltage in addition to increase in contrast ratio, birefringence, and band gap energy was observed after doping with alumina nanowires in both types of cells. Overall analysis shows that IPS cell configuration has more improved threshold voltage and contrast ratio in addition to decrease in birefringence and transmission intensity, as compared to planar cell configuration. No effect of cell configuration was observed on energy band gap and found same value for both planar and IPS cell configurations, as energy band gap is a material specific property.
关键词： threshold voltage,Nematic liquid crystal,energy band gap,In-plane switching,nanowires
更新于2025-09-23 15:21:01
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Comparative studies on polarisability, and optical properties of BiZnBo–SLS and PbZnBo–SLS glass
摘要： Soda Lime Silica (SLS), mainly composed of SiO2, was utilised in this study as the source of SiO2 for fabrication of glass. A study of physical and optical properties was performed for the glass system of x [RmOn] (0.50?x) [ZnO] 0.20 [B2O3] 0.30 [SLS], where RmOn are Bi2O3 and PbO with x = 0.05, 0.10, 0.20, 0.30, 0.40, and 0.45 mol. The glass was prepared by melt-quenching method. Optical properties of the glass samples were obtained using UV–visible absorption measurements. The main objective of this study was to compare the structural, polarizability, and optical properties of these two series synthesized silica based glass. The structure of the glass system was determined by X-ray diffraction (XRD). The density and molar volume were found to increase as Bi2O3 and PbO concentration increased. The optical band gap, Eopt values for bismuth glasses were between 2.58 and 2.92 eV and varied from 2.42 to 2.92 eV for lead glasses. The highest concentration of Bi2O3 and PbO in glass system showed the smallest Eopt. Bi2O3 glass exhibit the significant value towards direct or indirect band gap in optoelectronic field compared to PbO glass. Refractive index of glass samples was measured by UV–visible spectrophotometer. The value lay between 2.42 and 2.52 for bismuth glass and 2.42 and 2.57 for lead glass and the value increased as bismuth ion (Bi3+) and lead ion (Pb2+) concentration increased. Metallisation criterion was investigated on the basis of refractive index and band gap. The metallisation criterion of the glass sample linearly decreased with increasing concentration of bismuth and lead ions as a result of increasing number of refractive indices and decreasing number of band gap energy. The positive value of metallisation criterion indicates that the glass materials are insulators or not metallic. In conclusion, the obtained results show that the addition of bismuth oxide in silica glass improved its structural and optical properties compared to lead glass.
关键词： UV–visible,Polarizability,Refractive index,Metallisation criterion,Energy band gap
更新于2025-09-19 17:15:36
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Fabrication of Pure Sb2S3 and Fe (2.5%): Sb2S3 Thin Films and Investigation Their Properties
摘要： Pure Sb2S3 and Fe (2.5%): Sb2S3 thin films were synthesized on Zn2SnO4 coated with FTO conductive glasses using chemical bath deposition (CBD) technique. The X-ray diffraction (XRD) patterns obtained show that both thin films have an orthorhombic structure. Although the crystal structure of the two thin films was the same, the crystalline size of Fe (2.5%): Sb2S3 thin film (51.15 nm) was found to be smaller than that of pure Sb2S3 (52.89 nm). The effect of Fe-doped metal on crystal size of Sb2S3 was observed with this result. Another important observation is that the energy band gap of Fe (2.5%): Sb2S3 thin film (2.00 eV) is larger than that of pure Sb2S3 (1.89 eV). The photovoltaic properties of the synthesized thin films were examined by applying both incident photon-to-current efficiency (IPCE) and current density (J)–voltage (V) measurements. The obtained IPCE(%) values at 600 nm for pure Sb2S3 and Fe (2.5%): Sb2S3 thin films are 30.29 and 49.06, respectively. Using the J–V curves, the calculated η (%) values for pure Sb2S3 and Fe (2.5%): Sb2S3 thin films are 3.95 and 5.44, respectively. Based on the data obtained from both measurements, it was observed that the Fe dopant significantly enhance the performance of the Sb2S3-based solar cell devices.
关键词： Doping,Photovoltaic,Thin film,Particle size,Energy band gap,Synthesis
更新于2025-09-19 17:15:36
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Analysis of Defects and Surface Roughness on the Hydrogenated Amorphous Silicon (a-Si:H) Intrinsic Thin Film for Solar Cells
摘要： Effect of defect - through observation of energy absorption Urbach, on deposition rate, energy band gap, and surface roughness of intrinsic thin film are investigated using Radio Frequency Plasma Enhance Chemical Vapor Deposition (RF-PECVD). Films are grown on ITO (Indium Tin Oxide) glass substrate. Analysis of energy band gap is conducted to determine changes in the structure of a thin film of a-Si:H. Energy band gap is important to determine the portion of the spectrum of sunlight that is absorbed solar cells. From the characterization using UV-Vis spectrometer and the Tauc’s plot method, the width of the resulting energy band gap is greater if the hydrogen dilution is increased. It can be shown that the increase of the hydrogen dilution, will increase the energy band gap, and the surface roughness of thin layers. Instead, the improvement of the hydrogen dilution decrease the rate of deposition and Urbach energy. It is estimated that with greater hydrogen dilution, an intrinsic thin film of a-Si:H is more conductive for more reduction in residual of band tail defects or dangling bond defects.
关键词： RF-PECVD,a-Si:H,Energy band gap,Urbach energy,Hydrogen dilution
更新于2025-09-16 10:30:52
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Structural, optical and electrical studies of DC-RF magnetron co-sputtered Cu, In & Ag doped SnS thin films for photovoltaic applications
摘要： This work reports the tuning of optical and electrical properties of SnS through the incorporation of Cu, In and Ag atom without altering its chemical and crystal structural properties, using DC-RF magnetron co-sputtering technique with an in-situ substrate temperature of 400 °C. Doping is increased up to ~10% by varying the DC sputtering voltage as evident from EDAX analysis. Morphological studies show the variation in surface morphology, particle size and surface roughness due to the incorporation of dopant cation into SnS lattice sites. Film with optimized doping of ~5% resulted the substitutional doping of dopant cations (Cu2+, In3+ and Ag2+) into SnS lattice sites which resulted an improved absorption coefficient and hall carrier concentration with a decrease in band gap and electrical resistivity. Hall measurement studies of Cu 4.8% doped SnS film shows the p-type conductivity with lowest electrical resistivity of 90 Ω cm and improved carrier concentration of 1017 cm?3.
关键词： SnS thin films,Optical energy band gap,Co-sputtering,Electrical resistivity,Phase formation
更新于2025-09-11 14:15:04
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ion bombardment effect on the band gap of anatase TiO2 ultrathin films
摘要： We report a study of the effect of nitrogen ion bombardment on the optical properties of anatase TiO2 ultrathin films, particularly the band gap energy. The TiO2 films were prepared by a sol-gel method and dip-coating process. The as-prepared TiO2 films were then exposed to a +N2 low-energy ion beam from a microwave electron cyclotron resonance (ESR) ion source. Raman and spectroscopic ellipsometry (SE) analysis were performed on TiO2 films prepared at different +N2 exposure times. The Raman measurements reveal the conservation of the anatase TiO2 crystalline structure after the ion beam exposure. From a detailed ellipsometric study, the thickness of layers, the dielectric function, the band gap and the Urbach energies were determined. The obtained results show an increase of the TiO2 band gap with the decrease of thickness of films during +N2 exposure time. The band gap energy was blue shifted from 20 meV to 140 meV as the exposure time was increased from 5 min to 20 min when the thickness was decreased from 30 nm to 21 nm. This increasing of band gap energy could be explained by the thickness effect. From the band tail, the Urbach energy was also affected by +N2 ion beam. These results are in good agreement with the observed broadending of the Raman band the OeTieO bending vibration mode, as the exposure time increases.
关键词： +N2 ion bombardment,TiO2,Urbach energy,Band gap energy,Raman,Ellipsometry
更新于2025-09-09 09:28:46
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Influence of Post-deposition Heat Treatments on the Optical Properties of Chemically Deposited Nanocrystalline TiO2 Thin Films
摘要： The aim of this study is to investigate the potentials of TiO2 thin films for device applications. Nanocrystalline single phase of rutile TiO2 thin films have been prepared by Chemical Bath Deposition (CBD) technique at bath temperature range from 75-80°C, keeping other deposition variables constant. The films were then subjected to post-deposition heat treatments with annealing temperatures in the range 373 to 673 K. The optical characterisation was done using the Elmer Lambda-2 spectrometer to investigate the transmittance and absorbance versus wavelength measurements. The data obtained from the transmittance and absorbance measurements were used to deduce the important optical constants. The results show that the energy bandgap was direct, with values in the range ≤1.8 eV for the as-deposited layers and ≥2.2 eV for the annealed layers. At lower temperatures, the band gaps of the annealed samples did not differ significantly from the energy gap (1.8 eV) of the as-deposited film. At higher thermal treatment, the energy gaps increased with the increase in annealing temperatures and a maximum of 2.2 eV for the energy gap was determined for TiO2 film annealed at 673 K. The values of the energy bandgap obtained in study, are within the range suitable for application in photovoltaic solar cell devices and in related photonic applications.
关键词： thermal annealing,Energy band gap,solar cells,TiO2
更新于2025-09-04 15:30:14