Characterization of Polyaniline Based Polymer Light-Emitting Devices During Operation by Electrical Impedance Spectroscopy

摘要

Polyaniline was used as hole injection material for polymer light emitting devices (PLED) spin coated from a water based polyaniline/polystyrenesulfonate (Pani/PSS) dispersion. Data presented here were based on red, yellow, green and blue light emitting polymers (LEP). Depending on the applied bias voltages, the devices were studied by electrical impedance spectroscopy (EIS) in a wide frequency range. Experimental data could only be fitted by applying an equivalent circuit consisting of three RC elements in series. By separating the frequency dependent bulk and interface contributions, the bulk and junction resistance and capacitance were determined for various current densities. Variation in high interfacial capacitance was observed in the devices before and after stressing the PLEDs with a constant current of 10 mA/cm2 for 100 h.