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Author: search.filters.author.Kumara, R.

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    Co-sensitization performance of dye sensitized solar cell based on combination of natural dyes extracted from grapes and green tea
    (Faculty of Science, University of Kelaniya Sri Lanka, 2024) Shakya, M. D. P. A.; Jayathilaka, K. M. D. C.; Wanninayake, W. T. M. P. K.; Kumara, R.; Siripala, W. P; Wijesundera, L. D. B. R. P.
    The global energy crisis is a pressing issue that is likely to intensify in the future. Researchers are actively exploring alternative energy sources to create a more sustainable and secure future for the world's energy needs. The advantages of Dye Sensitized Solar Cells (DSSC) include simple, easy and cost-effective manufacturing, the ability to use flexible substrate, and the possibility to attain reasonable conversion efficiency. Their unique properties make them a promising solution for addressing energy shortages and advancing renewable energy technologies. The current efficiency of DSSCs is low, however dye modification can enhance their photoactive performance. Dye modification enhances the dye's optical characteristics and photoconductivity. Co-sensitization is a chemical approach to improve DSSC performance by using two or more dyes with distinct optical absorption properties. This study explores co-sensitized DSSC using natural dyes to enhance photoactive performance. The TiO2 was prepared by mixing TiO2 powder (Titanium (IV) dioxide), Acetic acid, and Ethanol. To study the effect of natural dyes on the photoelectric conversion efficiency of DSSCs, extracts of green tea and grapes were used as sensitizers. The photovoltaic characteristics of green tea and grape dyes were studied separately and then blended in a cocktail at four various volume ratios of tea and grapes dyes 1:4, 2:3, 3:2, and 4:1 to determine the best combination. The solar cell devices were characterized using absorbance spectra, electrochemical impedance, and current density-voltage (J-V) curves. UV-visible spectra were taken from the PekinElmer Ultraviolet and Visible Spectroscopy (UV/VIS) Lambda 365. J-V and electrochemical impedance spectroscopy measurements were taken with a Gammy series G 300 potentiostat using ELS300 software. A combination of green tea and grape dyes can increase absorbance and broaden the light absorption spectrum more than a single dye. The 1:4 tea-grape mixed dye demonstrated the best DSSC efficiency value as well as the highest photocurrent value. Cosensitization resulted in a conversion efficiency of 0.0198%, photocurrent density (JSC) of 230 µA/cm2, open circuit voltage (VOC) of 0.28 V, and fill factor of 30% while efficiency also increased from 0.0058% to 0.0198%. The results show that a higher anthocyanin composition relative to chlorophyll can improve DSSC efficiency. The impedance results show that the dye mixture decreases internal resistance, which is consistent with the observed cell efficiencies. Furthermore, the best results were obtained with an acidified cocktail at pH 3 with the same volume ratio of the non-acidified cocktails. Hydrochloric acid was used for acidification. The study reveals that co-sensitization holds significant potential for the future development of DSSCs.
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    Photocurrent improvement in grape dye sensitized solar cells by in cooperation of electrodeposited Cu particles in TiO2 photoanode
    (Faculty of Science, University of Kelaniya Sri Lanka, 2023) Shakya, M. D. P. A.; Jayathilaka, K. M. D. C.; Wanninayake, W. T. M. P. K.; Kumara, R.; Siripala, W. P.; Wijesundera, R. P.
    A worldwide effort is currently underway to address the world's energy crisis by finding sustainable energy alternatives. The Dye-Sensitized Solar Cell (DSSC) is a type of solar cell device that functions based on electrochemical principles and uses light sensitive dyes within its TiO2 photoelectrode layer to absorb light. The DSSC, one of the potential solutions, appears to be the most viable option for a future renewable energy source due to its sustainability and environmental friendliness. In cooperation of metal particles like Au or Ag in nano scale to the photoanode is one of the promising methods to improve the efficiencies of these DSSCs. Among these metal particles Cu has some distinct properties such as abundance, low toxicity, low cost and it undergoes Localized Surface Plasmonic Resonance (LSPR) effect like Au nanoparticles. Therefore, to improve the DSSC performances, in this study, Cu particle incorporation to the TiO2 electrode was carried out by electrochemical deposition method. Homogeneous TiO2 paste prepared by mixing appropriate amount of TiO2 powder (Titanium (IV) dioxide), ethanol, and acetic acid was deposited on a transparent Indium-doped Tin Oxide (ITO) conductive glass substrate by doctor blading method. Electrodeposition of Cu particles were potentiaostatically grown in the TiO2 electrode at -700 mV vs Ag/AgCl reference electrode using a three electrode electrochemical cell configuration with Pt as the counter electrode and 0.1 M sodium acetate and 0.01 M cupric acetate electrolyte at room temperature. Natural dye grapes have been used as sensitizer in the study. DSSCs were fabricated by sandwiching above TiO2 films with a C coated counted electrode using KI/I2 based electrolyte. The devices were characterized by analysing the UV – vis absorbance spectra and current density-voltage (J-V) curves and controlled potential coulometry measurements. The UV – vis absorbance spectrum revealed that the light absorption of DSSCs enhanced due to the incorporation Cu. The power conversion efficiency of 0.10%, photocurrent density (JSC) of 501 μA/cm2, open circuit voltage (VOC) of 0.47 V, and fill factor (FF) of 42% were achieved after the Cu incorporation in the photoanode. It is found that due to the incorporation of Cu particles, a slight voltage drop was visible, but there was a significant increase in the photocurrent density (JSC) from 308 μA/cm2 to 501 μA/cm2. The efficiency also increased from 0.07 to 0.10%. DSSC with the incorporated Cu particles showed 62% enhancement in the photocurrent compared to the DSSC without Cu particles.