Charge distribution in light emitting electrochemical cells

The performance of light-emitting electrochemical cells (LEC) is strongly influenced by the inhomogeneous distribution of the three main components (light emitting polymer, ion conductive polymer and ionic molecules) in the device. We report on the local ion distribution of lithium and triflate ions in a blend of the ionic conducting polymer poly (ethylene oxide) (PEO) and the conjugated polymer m-LPPP (methyl substituted poly (para phenylene)) by secondary ion mass spectroscopy(SIMS). In the system ITO/active layer/Al the ions are found to be located close to their counter electrodes. The behavior of these devices is investigated by impedance spectroscopy.