A dynamic model for injection and transport of charge carriers in pulsed organic light-emitting diodes

We develop a dynamic model to determine the delay time of electroluminescence (EL) from an organic light-emitting diode (OLED) under pulsed voltage. The model divides the delay time into two parts, the charge injection delay and the charge transport delay. The experimental observation of delay time for a bilayer OLED using LiF/Al as a cathode shows that the model is correct for studying the delay feature of EL under both low and high electric field conditions. We conclude that the charge transport process greatly contributes to EL delay, and the delay time correlates closely with the device area.