Electroluminescence Spikes of Pulsed Organic Light-Emitting Diodes at Switch-Off Using 1,4-Bis[2-[4-[N,N-di( p-tolyl)amino]phenyl]vinyl]benzene as a Light-Emitting Layer

The electroluminescence (EL) spikes from low-molecular organic light-emitting diodes (OLEDs) at the switch-off of applied pulse voltage using 1,4-bis[2-[4-[ N , N -di( p -tolyl)amino]phenyl]vinyl]benzene (DSB) as an emission layer were observed. The characteristics of EL spikes, such as their duration and magnitude, were studied by changing the device structure of the OLEDs and the conditions of the applied voltage. The duration of the EL spikes was found to depend on the species of electron transport layer but to be independent of the amplitude of the applied voltage. The magnitude of the EL spikes increased with the applied time up to a saturated state, which was significantly determined by the thickness of the emitting layer. The trapezoid pulse voltage was found to be an effective tool for predicting the charge accumulation in the interfacial layer.