Time-Resolved, Single Molecule Spectroelectrochemistry of Conjugated Polymers in Contact with ITO

Time-resolved, single molecule spectroelectrochemistry was used to study excited-state interfacial electron transfer between single conjugated polymer (MEH-PPV) molecules (possessing about 200 redox sites) and an indium tin oxide (ITO) electrode. Decay kinetics and emission yields were obtained while cycling the electrode potential in the range of -.5V to +.5V (Silver wire), which lies between the reduction (-1.5 eV) and oxidation potentials (0.8 eV) of the ground state. At +0.5 V, the emission intensities and average lifetimes were observed to increase about 20{\%} whereas at -0.5 V both values decrease by the same amount. Several possible origins of the potential-induced intensity modulation are proposed.