Doctoral Thesis
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.