Transient electroluminescence from poly(phenylenevinylene)-based devices

Electroluminescence (EL) from poly(phenylenevinylene) (PPV) films under the conditions of very strong electric field and very strong injection currents together with the use of strong voltage pulses to achieve electrically pumped lasing are described. Essential conditions for efficient and stable light emitting diodes (LED) are high mobilities, efficient injection and stable polymers. The charge carrier mobility in PPV under moderate electric fields is relatively low. However, the mobility is field-dependent and may increase by several orders of magnitude upon increasing the pulse height. A new mechanism for device degradation and failure in polymer LEDs under the strong pulses is compared to DC-operated LEDs.