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Browsing Natural Sciences by Author "Abubakari, Ismail"

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    Alizarin-based dyes for dye-sensitized solar cells application
    (The University of Dodoma, 2021) Abubakari, Ismail
    The advancement in dye-sensitized solar cells technology involves the discovery of new materials with reduced cost and improved performance in terms of solar energy absorption and conversion. This study presents the development of a novel dye molecule based on alizarin for dye-sensitized solar cells. The dye was first designed using Gaussian 09W package before its synthesis. The designing was involving organic compound; alizarin, 4-(benzo[c][1,2,5]thiadiazol-4-yl)benzoic acid, 2-hexylthiophene and carboxylic acid and metals; chromium, iron, copper, zinc and ruthenium to produce organic and organometallic compounds. Different properties including intramolecular charge transfer, absorption properties and photovoltaic properties were analysed to come up with the best dye for synthesis among several dyes designed. Seventeen dye molecules were successful designed with their properties recorded and reported while the best molecule labelled OG3 was successful synthesized as a brownish-orange solid. Together with the synthesized dye, all designed dyes found potential sensitizer in dye-sensitized solar cells with positive outcomes upon electron excitation and injection to semiconductors and successive regeneration by the electrolyte. Moreover, the molecules composed of substituent 2-hexylthiophene were generally better performer compared to others with different substituents. The charge transfer was found spontaneous from the attached groups and unsubstituted ring of alizarin to the substituted rings of alizarin possessing C=O groups. This confirms C=O to be the anchoring groups facilitating binding of dyes to the semiconductor surface hence strengthening the dye-semiconductor interactions. The synthesized dye OG3 was characterized before subjected to photocurrent-photovoltage analysis. Generally, the synthesized dye confirmed to be useful in DSSC applications with short circuit current, open circuit voltage and fill factor of 0.0146 A/cm2, 0.65 V and 0.612, respectively. The conversion efficiency of the cell fabricated using OG3 was found to be 5.81 % under 100 mW/cm2 solar illuminations.
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    Optical and photovoltaic properties of substituted alizarin dyes for dye-sensitized solar cells application
    (Taylor & Francis, 2020) Abubakari, Ismail; Babu, Numbury Surendra; Vuai, Said; Makangara, John
    This paper presents the theoretical study on photovoltaic and absorption properties of alizarin derivatives. Optimization of structures and calculations were performed by density functional theory and time-dependent density functional theory using B3LYP hybrid functional and 6–31 G (d,p) basis set. The dyes were formed by substituting 2-hexylthiophene mixed with carboxylic acid and 4-(benzo[c][1,2,5]thiadiazol-4-yl)benzoic acid. The performed substitution shows improvement in most of the properties. The highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of molecular dyes showed positive effect upon electron injection to semiconductor and subsequent regeneration by the electrolyte. Almost all necessary and important parameters to demonstrate the usefulness of molecular dyes as photo-sensitizers are detailed discussed. Based on the discussion and analysis, all considered molecules are proved to be useful in dye-sensitized solar cells using TiO2 semiconductor and I−/I−3 couple electrolyte. Collectively, dyes DY3 and DY2 showed better results than others with LHE and V oc of 0.2142 and 0.6722 eV, respectively, for DY3 and 0.7033 and 0.6224 eV, respectively, for DY2.
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    Synthesis and photocurrent density–photovoltage (J–V) characterization of a novel alizarin derivative dye for dye-sensitized solar cell technology
    (Springer, 2022) Abubakari, Ismail; Babu, Numbury Surendra; Vuai, Said; Makangara, John
    Dye-sensitized solar cells technology has attracted extensive academic scholars’ interests due to their potential low-cost solar energy harvesting. Increasing performance of dye-sensitized solar cell needs more efficient dye to maximize solar energy absorption. This work presents the synthesis and J–V characterization studies for a novel alizarin derivative dye HDD. The dye was formed by the reaction between brominated alizarin and 5-hexyl-2-thiopheneboronic acid pinacol ester. The final dye product was successfully synthesized as brownish-orange solid. Characterization of the synthesized dye was done using spectroscopic techniques; mass spectrometry, infrared spectroscopy and nuclear magnetic resonance before photovoltaic performance investigation. The dye was found to be useful as photo-sensitizer in dye-sensitized solar cell through calculation of conversion efficiency. Generally, the dye HDD showed better results in terms of photovoltaic properties with open-circuit voltage, short-circuit current density and fill factor of 0.65 V, 0.0146 A/cm2 and 0.612, respectively. The conversion efficiency of the cell using the synthesized dye HDD was found to be 5.81% under 100 mW/cm2 solar illuminations.