Synthesis of a novel bipyrimidine dicarboxylic acid ligand for the preparation of panchromatic ruthenium dyes

Abstract

A novel ruthenium complex with a new 4,4′-bipyrimidine-6,6′-dicarboxylic acid ligand (H2dcbpm) has been synthesized and its properties were investigated for application in dye-sensitized solar cells. The new dye shows a wide range of absorption of the solar spectrum with maximum of absorption at 665 nm corresponding to a 100 nm redshift compared to the precursor complex ([Ru(dcbpyH2)2(Cl)2]) of the commercial N719 dye. The energies of HOMO-LUMO obtained by voltammetry and DFT calculations show an overall stabilization of the orbitals of the bipyrimidine complex compared to the bipyridine one. Despite having promising absorption properties, the redox potentials of this complex make it unsuitable for charge injection into the conduction band on TiO2. Nevertheless, the newly prepared ligand provides an additional tuning path to adjust the energy levels of the complex in order to benefit from the red-shifted absorption it offers.