Deactivation of the ruthenium excited state by enhanced homogeneous charge transport: implications for electrochemiluminescent thin film sensors

The electrochemiluminescent (ECL) performance of three ruthenium-based metallopolymer platforms with different homogeneous charge transfer diffusion coefficients (D_CT) is reported. Significantly, simultaneous detection of light and current in tandem with steady-state photoluminescence studies demonstrate that increasing the rate of Ru³⁺ production via enhanced charge transport results in a decrease in ECL intensity of up to 82% when the concentration of the co-reactant, sodium oxalate, is low, i.e., sub-mM. Spectroelectrochemical studies demonstrate that for maximum sensitivity to be obtained, the electroactive properties of the polymeric support matrix need to be considered in tandem with luminophore, analyte and co-reactant concentrations.