Faculty of Science and Agriculture

Permanent URI for this communityhttp://hdl.handle.net/20.500.11837/153

Browse

Browsing Faculty of Science and Agriculture by Author "Ajibade, P.A."

Filter results by typing the first few letters
Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    Synthesis, characterization and evaluation of Ru(II) and Co(II) complexes of some nitrogen chelating ligands as sensitizers for dye sensitized solar cells (DSSCs).
    (2015) Motaung, Mathato Petronella; Ajibade, P.A.
    The demand for fossil fuels has resulted in decrease in natural resources and created negative impacts on the environment. These negative impacts require the development of alternative sources of energy that are environmentally friendly. Dye sensitized solar cells (DSSCs) is a new class of renewable source of clean energy that is environmentally friendly with relatively low-cost. DSSC is one of the most promising solar cell devices with incident to power conversion efficiency of up to 13%. The highest efficiency of DSSC has been obtained by using a sintered TiO2 semiconductor with Zn based porphyrin dye (SM315) as sensitizers. Five nitrogen chelating ligands containing 2,6-bis-(benzimidazolyl)pyridine (L1), 2,6-bis-(butylbenzimidazolyl)pyridine (L2), 2,6-bis-(benzylbenzimidazolyl)pyridine (L3), 2,6-bis-(pyrazolyl)pyridine (L4), 2,6-bis-(3,5-dimethylpyrazolyl)pyridine (L5), and their corresponding ruthenium(II) and cobalt(II) complexes have been synthesized and characterized by elemental analysis, conductivity measurements, melting point, FTIR and NMR spectroscopy. The photophysical and electrochemical studies of the metal complexes were carried out by UV-Vis, photoluminescence and cyclic voltammetry. The FTIR spectroscopic studies confirmed the coordination of the ligands to the Ru(II) and Co(II) metal ions. The results of the electronic spectra studies show that the complexes are coordinated to the ligands in six coordinate octahedral geometry and th complexes exhibited some photoluminescence properties of suitable for application in dye sensitizers. The cyclic voltammogram of complexes containing 2,6-bis-(benzimidazolyl)pyridine have more reduction potentials which could be ascribed to the increased π conjugation in the ligands used for the synthesis of the complexes. The solar cell efficiencies of the complexes was calculated from the I-V curves of fabricated solar cells. The solar cell fabricated from complex C5 (ruthenium complex of 2,6-bis-(3,5-dimethylpyrazolyl)pyridine) on TiO2 semiconductor produced the highest open-circuit photovoltage of 87.3 × 10-3 mV, short-circuit photocurrent of 0.022 mA/cm-2 and the solar conversion efficiency was 1.01 × 10-3 %.