Dye extracted from Costus woodsonii leave as a natural sensitizer for dye-sensitized solar cell

Current work employs dye extracted from leaves of Costus woodsonii as a new sensitizer for dye-sensitized solar cells (DSSCs). The leave was extracted in three different solvents namely ethanol, methanol, and acetone. Extraction of leaves was carried out by the freezing method. DSSCs with the configuration of TiO2/dye/electrolyte/Pt were assembled. The dyes in DSSCs were Costus woodsonii leaves extracted in methanol, ethanol, and acetone. DSSC with methanol extract of leaves has an efficiency of 0.23 % and short-circuit current density (Jsc) of 0.63 mA cm-2. DSSC sensitized with ethanol extract of leaves has an efficiency of 0.37 % and Jsc of 0.85 mA cm-2. DSSC sensitized with acetone extract of leaves shows the highest efficiency of 0.48 % and Jsc of 1.35 mA cm-2. The performance of the DSSCs in this work is compared with other natural dye-based DSSCs. The efficiency obtained in this work is better or at par with the works reported by other researchers. Keywords: Natural dye; Costus woodsonii; Leave; Dye-sensitized solar cells

Photocatalytic activity of graphene oxide–TiO 2 thin films sensitized by natural dyes extracted from Bactris guineensis

This study synthesized and characterized composites of graphene oxide and TiO 2 (GO–TiO 2 ). GO–TiO 2 thin films were deposited using the doctor blade technique. Subsequently, the thin films were sensitized with a natural dye extracted from a Colombian source ( Bactris guineensis ). Thermogravimetric analysis, X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance measurements were used for physico-chemical characterization. All the samples were polycrystalline in nature, and the diffraction signals corresponded to the TiO 2 anatase crystalline phase. Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) verified the synthesis of composite thin films, and the SEM analysis confirmed the TiO 2 films morphological modification after the process of GO incorporation and sensitization. XPS results suggested a possibility of appearance of titanium (III) through the formation of oxygen vacancies (O v ). Furthermore, the optical results indicated that the presence of the natural sensitizer and GO improved the optical properties of TiO 2 in the visible range. Finally, the photocatalytic degradation of methylene blue was studied under visible irradiation in aqueous solution, and pseudo-first-order model was used to obtain kinetic information about photocatalytic degradation. These results indicated that the presence of GO has an important synergistic effect in conjunction with the natural sensitizer, reaching a photocatalytic yield of 33%.

Performance Enhancement of Dye-Sensitized Solar Cells Using a Natural Sensitizer

Dye-sensitized solar cells (DSSCs) based on natural sensitizers have become a topic of significant research because of their urgency and importance in the energy conversion field and the following advantages: ease of fabrication, low-cost solar cell, and usage of nontoxic materials. In this study, the chlorophyll extracted from papaya leaves was used as a natural sensitizer. Dye molecules were adsorbed by TiO2 nanoparticle surfaces when submerged in the dye solution for 24 h. The concentration of the dye solution influences both the amount of dye loading and the DSSC performance. The amount of adsorbed dye molecules by TiO2 nanoparticle was calculated using a desorption method. As the concentration of dye solution was increased, the dye loading capacity and power conversion efficiency increased. Above 90 mM dye solution concentration, however, the DSSC efficiency decreased because dye precipitated on the TiO2 nanostructure. These characteristics of DSSCs were analyzed under the irradiation of 100 mW/cm2. The best performance of DSSCs was obtained at 90 mM dye solution, with the values of Voc, Jsc, FF, and efficiency of DSSCs being 0.561 V, 0.402 mA/cm2, 41.65%, and 0.094%, respectively.