Tailoring optical bandgap of ZnO nanostructured thin films doped with different elements facilitates potential material for photonic applications. Different methods of fabrication process result in different optical and structural properties for the same amount of Mg content. Therefore, details investigation of structural and optical parameters, and their correlation need to be revealed to utilize the fabricated thin films. In this work, Mg-doped ZnO thin film of 200Â nm thickness was fabricated by sol-gel spin coating method on a glass substrate for four different Mg content levels. Multiple layers were deposited by a spin coater to increase the film thickness. The prepared thin films were characterized by SEM, XRD, EDS, and UVâVis spectroscopy. The spectroscopic analysis showed a uniform crystalline nanostructured surface with less structural defects, enhanced transmittance, and higher optical bandgap than that of pure ZnO nanostructured thin film. Change of Mg content from 2% to 8% facilitated tuning of bandgap in the range of 3.30â3.39Â eV. Changing trend of structural and optical parameters with Mg content showed non-linear, non-monotonic relation. In-depth analysis of structural and optical properties provides crucial information to form a better view about bandgap dependency on structural parameters.

In this study, natural dye sensitizer based solar cells were successfully fabricated and photovoltaic performance was measured. Sensitizer (turmeric) sources, dye extraction process, and photoanode sensitization time of the fabricated cells were analyzed and optimized. Dry turmeric, verdant turmeric, and powder turmeric were used as dye sources. Five distinct types of solvents were used for extraction of natural dye from turmeric. Dyes were characterized by UVâVis spectrophotometric analysis. The extracted turmeric dye was used as a sensitizer in the dye sensitized solar cellâs (DSSC) photoanode assembly. Nano-crystalline TiO2 was used as a film coating semiconductor material of the photoanode. TiO2 films on ITO glass substrate were prepared by simple doctor blade technique. The influence of the different parameters VOC, JSC, power density, FF, and η% on the photovoltaic characteristics of DSSCs was analyzed. The best energy conversion performance was obtained for 2 h adsorption time of dye on TiO2 nano-porous surface with ethanol extracted dye from dry turmeric. Keywords: DSSC, Natural dye, TiO2 photoanode, Dye extracting solvent, Dye-adsorption tim

Use of Degussa P25 titanium-dioxide nanopowder in dye-sensitized solar cell (DSSC) photoanode improves efficiency of the DSSC cell. Annealing of titanium dioxide is required for fabrication of crystalline mesoporous thin film photoanode on transparent conducting glass using doctor blade method. Different annealing temperatures provide different structural, morphological, and optical properties of the photoanode, which may influence the efficiency of the cell. In this paper, energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and UV-Vis-NIR spectroscopicanalysis have been carried out to investigate annealing temperature effect on various structural parameters, mole-fraction, phase-content, and optical bandgap of the TiO₂film photoanode. It was observed that depending on annealing temperature, theratio of polymorphs of Degussa P25 changed substantially. For the change in annealing temperature from 350 °C to 600 °C, variations occurred in crystallite size from 11.9 nm to 24.9 nm, strain from 0.006 to 0.014, specific surface area from 62.77 m²·g^-1to 125.74 m²·g^-1, morphology index from 0.49 to 0.64, dislocation density from 5 × 10¹³line/m²to 8 × 10¹⁵line/m², crystallite per unit surface area from 2 × 10¹³m^-2to 2.5 × 10¹⁴m^-2, and optical bandgap from 2.4 eV to 3.1 eV.

This work proposes a modeling of self-assembled monolayers (SAMs) to assess the quality of SAM layers in terms of their leaky behavior. In the modeling, electrochemical impedance spectroscopy (EIS) and a conceptual and simplified resistance-resistance-capacitance (RRC) electrical model from an electrochemical setup were demonstrated. Based on the model, Matlab-based simulation was carried out to find out the suggestive low frequency measurement for analyzing the defective monolayers. Finally, the developed electrical model facilitated the interpretation of the EIS spectra measured in the range of 10 Hz to 100 kHz and provided the capacitance, resistance and thickness of the monolayer. Thus the proposed model could be considered as a powerful tool to characterize the defective SAMs, which was very specific to determine the resistive behavior of the self-assembled monolayers prepared for shorter adsorption time. Keywords: Self-assembled monolayers (SAMs), Octadecanethiol (ODT), Hexadecanethiol (HDT, Impedance, Capacitance of the SAM (CSAM), Resistance of the SAM (RSAM

Zinc oxide thin films with different thicknesses were prepared on microscopic glass slides by sol-gel spin coating method, then hydrothermal process was applied to produce zinc oxide nanorod arrays. The nanorod thin films were characterized by various spectroscopic methods of analysis. From the images of field emission scanning electron microscope (FESEM), it was observed that for the film thickness up to 200 nm the formed nanorods with wurtzite hexagonal structure were uniformly distributed over the entire surface substrate. From X-ray diffraction analysis it was revealed that the thin films had good polycrystalline nature with highly preferred c-axis orientation along (0 0 2) plane. The optical characterization done by UV-Vis spectrometer showed that all the films had high transparency of 83 % to 96 % in the visible region and sharp cut off at ultraviolet region of electromagnetic spectrum. The band gap of the films decreased as their thickness increased. Energy dispersive X-ray spectroscopy (EDS) showed the presence of zinc and oxygen elements in the films and Fourier transform infrared spectroscopy (FT-IR) revealed the chemical composition of ZnO in the film.