Browsing by Author "Ariyasinghe, Y.P.Y.P."

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    Identification and Characterization of Natural Dyes Available in Sri Lanka and Their Usage in Low Cost Dye Sensitized Solar Cell
    (Uva Wellassa University of Sri Lanka, 2010) Suganthy, P.; Wijayarathna, T.R.C.K.; Ariyasinghe, Y.P.Y.P.; Senadeera, G.K.R.
    The dye-sensitized solar cell (DSC) is a third generation photovoltaic device that holds significant promise for the inexpensive conversion of solar energy to electrical energy, because of the use of inexpensive materials and a relatively simple fabrication process. Most of the researchers in this field use Ruthenium complex as dye in these DSCs. However, Ruthenium is a rare metal, therefore, ruthenium-based compounds are relatively expensive. In this work, we explore the use of natural dyes obtained from various fruits, flowers and plants from Sri Lanka in these solar cells aiming to use these cells in low power and low cost biocensing applications. DSCs sensitized with several natural dyes extracted from fruits, leaves and flowers, showed photocurrent densities (Jsc) and photovoltages (Voc) ranging from 4.312 to 0.036 mAcm-2, and from 595.9 to 370.3 mV under the illumination of 100 mWcm-2 respectively. The corresponding efficiencies were ranged from 1.022 to 0.011%. While the DSSCs sensitized by acidified (pH<1) Begonia extracts showed the best cell performances giving a Jsc of 4.312 mA cm-2, with 428.7 mV photo voltage and an efficiency of 1.022%, the cells sensitized with acidified lxora coccinea delivered 2.126 mA cm-2 and 435.1mV as a photocurrent density and photovoltage respectively, with an efficiency of 0.446% under the above illumination. The maximum light absorption wavelength of the begonia dye found to be was around 522 nm and incidentally it was very close to the absorption peak position of the commercially available successful Ru (N3) dye. This peak position was red shifted to the higher wavelengths giving enhanced photocurrent out puts due to the acidification of the dye solution. The calculated energy gap between the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital level (LUMO) for the dye extracts obtained from Begonia was 2.25 eV. Key Words: Dye sensitized solar cell, Natural dyes, Low cost, acidified Begonia extracts, lxora coccinea
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    Synthesis and Characterization of Polymer Electrolytes for Dye Sensitized Solar Cells
    (Uva Wellassa University of Sri Lanka, 2010) Gunasekara, H.D.N.; Wijayarathna, T.R.C.K.; Ariyasinghe, Y.P.Y.P.; Senadeera, G.k.R.
    The search for renewable sources of energy has led to an increasing interest in photochemical cells (PECSs) because of their possible role as transducers of solar to electrical energy. PECSs fabricated with dye sensitized (DS) nanoporous films of semiconductors have been studied extensively throughout the last decade, in attempts to make efficient low cost alternatives to the silicon solar cell. Although practically viable efficiencies have achieved, the liquid electrolyte in DS PECSs presents problems which have not been resolved satisfactorily. In this context many researchers including our group have tried to replace the electrolyte with inorganic hole conductors and polymeric quasi solid electrolytes. As an continuation of that, in this study, to obtain the best, solidified polymeric electrolyte to be used in dye DS PECSs applications, the effect of solidification, crystallinty, redox couple concentration, choice of cations and additives in the solar cell performances were investigated by fabricating polymeric electrolytes Comprising with poly (acrylonitrile) (PAN) and tested them with the DS solar cells having a configuration FTO/Ti02- Ruthenium Dye/Polymer electrolyte/Pt-FTO. The best composition of the polymer electrolyte giving highest efficiency was PAN (9.98%)/EC (ethylene carbonate, 39.92%)/PC (Propylene carbonate, 39.92%)/Lil (9.98%02 (0.20%) (by weight) which yields on overall energy-conversion efficiency of about 4.53% under the irradiance of 100 mW cm-2. The introduction of the nano sized ceramic filler TiO2 effectively enhanced the performance of the cell efficiency up to 4.80% .The morphology, structure, and conductivity studies were examined by, X-ray diffraction (XRD), FTIR and AC impedance techniques. X-ray Diffraction result has shown that the electrolytes with TiO2 filler has an amorphous structure and no crystalline peaks were observed. The addition of TiO2 significantly enhanced the conductivity of the electrolyte showing 5.58x10-3S cm-1. Key words: Dye sensitized solar cell, Polymer Electrolytes, poly (acrylonitrile) (PAN), FTO/Ti02-Ruthenium Dye/Polymer electrolyte/Pt-FTO, TiO2 filler