M. Khalid Hossain

Annealing temperature effect on structural, morphological and optical parameters of mesoporous TiO2 film photoanode for dye-sensitized solar cell application

Abstract 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 TiO2 film 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-1 to 125.74 m2·g-1, morphology index from 0.49 to 0.64, dislocation density from 5 × 1013 line/m2 to 8 × 1015 line/m2, crystallite per unit surface area from 2 × 1013 m-2 to 2.5 × 1014 m-2, and optical bandgap from 2.4 eV to 3.1 eV.

Influence of natural dye adsorption on the structural, morphological and optical properties of TiO2 based photoanode of dye-sensitized solar cell

Abstract Porous photoanodes of dye-sensitized solar cells (DSSCs) can adsorb specific type of natural or organic dyes. Adsorption of the dye results in a change of the structural, morphological and optical characteristics of the photoanode. In this work, we present a comparative study on the adsorption effect of natural dye (Curcuma Longa sp.) on the structural, morphological and optical properties of mesoporous titanium dioxide (TiO2) photoanode on indium tin oxide (ITO) coated glass. A number of investigations including XRD, UV-Vis spectroscopy, EDS, and SEM were carried out to observe the variations due to adsorbed dye on TiO2 surface. XRD characterization revealed the effect of dye adsorption on specific surface area (SSA), crystallite size, and morphological index (MI). In this case, increasing SSA with decreasing particle size was found for both dye adsorbed and dye free DSSC photoanode samples. Also, the MI and SSA were found to be directly and inversely proportional to the crystallite size respectively. UV-Vis-NIR spectroscopy showed that dye adsorption changes the light absorption, transmittance, and optical bandgap of the photoanode. Average atomic mass percentage of titanium (Ti) and oxygen (O) obtained from EDS analysis proved the presence of TiO2 in the mesoporous photoanode. In SEM images, significant morphological changes of mesoporous TiO2 surface appeared because of dye adsorption.

Efficiency enhancement of natural dye sensitized solar cell by optimizing electrode fabrication parameters

Abstract Efficiency of dye-sensitized solar cell (DSSC) depends on several interrelated factors such as type and concentration of dye, type and thickness of photoelectrode and counter electrode. Optimized combination of these factors leads to a more efficient cell. This paper presents the effect of these parameters on cell efficiency. TiO2 nanoporous thin films of different thicknesses (5 μm to 25 μm) were fabricated on indium doped tin oxide (ITO) coated glass by doctor blading method and characterized by inverted microscope, stylus surface profiler and scanning electron microscope (SEM). Natural organic dye of different concentrations, extracted from turmeric, was prepared with ethanol solvent. Different combinations of dye concentrations and film thicknesses along with different types of carbon catalyst have been investigated by I-V characterization. The result shows that the cell made of a counter electrode catalyst material prepared by candle flame carbon combined with about 15 μm thick photoelectrode and 100 mg/mL dye in ethanol solvent, achieves the highest efficiency of 0.45 %, with open circuit voltage of 566 mV and short circuit current density of 1.02 mA/cm2.

Smart nanocarrier-based drug delivery systems for cancer therapy and toxicity studies: A review

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