Turn on behavior of light emitting electrochemical cells

In light emitting electrochemical cells (LECs) the turn on voltages both for current and electroluminescence depend on different parameters, like the polymer energy gap or the dissociation free energy of the salt. We report investigations of the behavior of salt dissociation in blends of optimized LECs, where the luminescent and the ionically conducting polymer form a heterogenous morphology in order to improve the response times of the LECs and present the results of infrared measurements (IR) on the active layer of these LECs. We compare them with results of infrared measurements of the active layer of LECs where short ethylene oxide side chains are attached on the backbone of the conjugated polymer in order to investigate the kind of ionic species being present.