Papers by Keyword: Optical Transmittance

Abstract: The study investigated the effect of iodine-doped pentacene film as a buffer layer in an organic light-emitting diode (OLED). In this study, an ITO (indium tin oxide)-based sample is used as a reference device for comparative purposes. In OLED devices, the buffer layers were deposited using the doping of iodine vapor with the pentacene materials under proper conditions. The thermal treatment of the doped pentacene film results in increasing the conductivity of the buffer layer. Surface morphology for the bilayer anode was carried out by FESEM (Field Emission Scanning Electron Microscope) analysis. In our work, maximum luminance of 2345 cd/m² and current efficiency of 5.4 cd/A are obtained, along with more stability performance under annealing treatment in the device structure of FTO/iodine-doped pentacene (30 nm)/TPD [N, N′-Bis(3-methyl phenyl)-N, N′-diphenylbenzidine] (44 nm)/Alq3 [Tris(8-hydroxyquinoline)aluminum(III)] (52 nm)/LiF (lithium fluoride) (5 nm)/Al (aluminum) (110 nm).

Abstract: In this work, electrospun membrane with excellent optical transparency has been developed and the study focuses on the optical and electromechanical properties of the membrane. Highly transparent PVDF based membrane fabricated by electrospinning exhibited appreciable piezoelectric property. Thus the study mainly focus on the multifunctional behaviour of these nanomembrane in the field of transparent sensors and energy harvesting systems. The transmittance of the fabricated membrane is measured using spectrophotometer and beta sheets content associated with the piezo activity of the membrane is measured using the Fourier Transform Infrared spectra. The surface characterization of the electrospun membrane were performed using Scanning Electron Microscope (SEM). The piezo response range of these membrane were tested using impulse loading and force voltage-based measurements. The utilization of these transparent optical membranes in the field of micro and nanoenergy harvesting systems based on piezoelectric transduction mechanism is focused.

Abstract: Gallium oxide (Ga₂O₃) nanowires were grown on fused quartz and Si substrates by a vapor transport method of heating gallium metal at 750−1100 °C in a tube of the horizontal furnace. The obtained white colored product has shown to be the Ga₂O₃ nanowires with average diameters ranging from 30 to 80 nm. The optical transmittance spectra indicated that the bandgap energy of Ga₂O₃ nanowire increases as the diameter of nanowire decreases.

Abstract: High aspect ratio silver nanowires (AgNWs) with an average length of 40 μm and average diameter of 88 nm were successfully synthesized using waste ethylene glycol as solvent and reducing agent. Silver nanowires with an average length and diameter of 32 μm and 122 nm, were produced after the third cycle of being reused. A transparent conducting film with a sheet resistance of 69 Ω/sq and optical transmittance of 91% was fabricated by Meyer rod coating an ink formulation of AgNWs dispersed in hydroxyethyl celullose (HEC)/methanol/deionized water. The low resistance of the AgNW networks was maintained even after 1000 bending cycles due to HEC acting as binder for the nanowires. The AgNWHEC transparent conductive electrode performed better than bare AgNWs and indium tin oxide (ITO) on polyethylene terephthalate (PET) substrate after several bending cycles. The AgNW-HEC electrode also showed excellent stability against corrosion.

Abstract: W-doped VO₂ films were prepared by DC reactive magnetron sputtering with various substrate bias. The microstructure, surface morphology, electrical and optical performances of the films were characterized by x-ray diffraction, scanning electron microscope, four-point probe method and spectrophotometer, respectively. The effect of substrate bias on microstructure, electrical and optical properties of sputtered W-doped VO₂ films was studied. The XRD results reveal that all samples exhibit preferential VO₂ (011) lattice orientation except the as-grown sample in our experiment. All the samples applied substrate bias show some degree optical switching performance in IR range, while the thermochromic phenomena was observed from resistance-temperature dependence plot only for the samples of substrate bias varied from-100V to-200V. This indicate that the optical and electrical properties of W-doped VO₂ films have different sensitivity to substrate bias. Optimal substrate bias of-200V sample shows fine semiconductor-metal-transition performance.

Abstract: This work examines the modification of the structural and optical properties of ZnO thin films by control of deposition and post-treatment parameters. ZnO thin films were deposited by RF magnetron sputtering from a ceramic target locally made at SHESTCO in Abuja, Nigeria. X-ray diffraction measurements characterized the different films prior to thermal annealing as extremely amorphous with average UV-VIS transmittance spectra between 80 and 90%. Annealing at different temperatures and time spans influenced the formation of Wurtzite (002) oriented ZnO crystallites. Contrary to the crystallinity of the films, which was strongly influenced by the deposition power, the optical transmission of the films was only slightly influenced by the deposition power and it was less sensitive to the crystallinity of ZnO thin films.

Abstract: Using solvothermal method to modify the surface of polymethyl methacrylate (PMMA), the silica films were prepared on it via sol solution and solvothermal treatment. Silica-based hybrid sol solutions were synthesized from tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS). The obtained silica-based hybrid films consisted of the uniform particles around 40 nm in diameter observed by atomic force microscopy (AFM). The optical property was evaluated by the UV-Vis absorption spectra. The silica hybrid films prepared through this process showed good optical transmittance.

Abstract: ATO thin films have been successfully prepared by the spin coating method using an ethanol solution of SnCl₄∙5H₂O and SbCl₃ using acetylacetone as hydrolysis modifier. ATO films from 1 to 6 layers were prepared at 300 °C as densification temperature and within an annealing temperature ranging from 450 °C to 750 °C. Films exhibited the cassiterite crystalline phase and morphology consisted in nanoparticles of about 10 nm in diameter. Acetylacetone content as well the addition of water affected the particle size and morphology, decreasing particle size and the appearance of voids. Films prepared at an acetylacetone ratio of 4 with no addition of water exhibited an optical transparency above 90% from 380 to 800 nm while resistivity was 7.99 x10-3 Ω∙cm. The effect of the hydrolysis modifier on the electric properties, morphology, optical transparency and microstructure has been studied

Abstract: Aluminum-doped zinc oxide (AZO) films were deposited on polyethylene terephthalate (PET) by radio frequency magnetron sputtering. The influence of the various deposition parameters (R.F. power, substrate-to-target distance, substrate temperature, deposition time) on electrical, morphological and optical properties of AZO/PET films was investigated. The use of grey-based Taguchi method to determine the optimization of the process parameters by considering multiple performance characteristics has been reported. The electrical resistivity and the average transmittance of the AZO films were improved by increasing the substrate temperature. Finds based on the grey relational analysis show that the lowest electrical resistivity of AZO films to be about 1.6 × 10^-3Ω-cm, and visible range transmittance about 80%.

Abstract: LaAlO₃ translucent ceramics were fabricated with solid-state reaction method and sintered in vacuum condition. The powders are synthetized at 1200°C. There are almost no pores in the grains of ceramics sintered at 1750 °C. But the ceramics have few La₂O3 second phase. The highest transmittance is 22%. The low transmittance may be caused by scattering losses of La₂O₃ second phase.