One-pot synthesis, photophysical, electrochemical and molecular property of mixed-ligands ruthenium complex functionalities: Potential materials for dye-sensitized solar cells (DSSCs)
Adewale O. Adeloye, Simplice Koudjina, Vipin Kumar, Kgaugelo C. Tapala, Joachim Gbénou, Prabhakar Chetti
Abstract
ABSTRACT In our search for excellent photoactive materials for optolectronic applications such as dye-sensitized solar cells, four highly emissive, new fluorescent ruthenium coordinated dye complexes ( A-D ) having pyridyl-3,5-dicarboxylic acid and triphenylphosphine as the two common monodentate ligands formulated as RuCl 2 (PPh 3 ) 2 (dca) 2 , RuCl 2 (PPh 3 )Bpy(dca), RuCl 2 (PPh 3 )Hbpy(dca) and RuCl 2 (PPh 3 )Phen(dca) were prepared in a one-pot synthetic method, purified and characterized by IR, UV-Vis, PL, 1 H, 13 C, 31 P- NMR spectroscopy, elemental analysis electrochemistry and mass spectrometry. The UV-Vis absorption spectra revealed three to four well-define absorption peaks in the region 265–560 nm which were assigned to the π–π* transitions, two ligand-to-ligand charge-transfer (LLCT) bands and dπ(Ru)–π*(L) transitions respectively. High intensity and broad emissive photoluminescent properties in the mid-infrared region (> 640 nm) were recorded for all complexes. The electron-donating and/or electron-withdrawing ability of the carboxylic acid and chloride groups present in the complexes possibly favoured a one-electron oxidation reaction, stability of Ru 3+ /Ru 2+ redox properties and the potential of their applications in dye-sensitized solar cells and/or optoelectronics. The calculated results suggest that the frontiers Molecular Orbitals (FMOs), open-circuit voltage ( ), light-harvesting efficiency ( ), driving force for electron injection ( ), dye driving force regeneration ( ), molecular electrostatic potential (MESP), and density of states ( ) are affected by substituents groups introduced in the ruthenium complex. The of all the dyes are theoretically calculated at J SC 9, 12, and 15 mA cm -2 to give the higher power conversion efficiency ( ) of the solar cell obtained for dye B at (9.36 %). The comparative investigation shows that extended π-spacer variation in the ligands is essential in the fine-tuning of the overall performance of the DSSCs in the ruthenium complexes.