Monte Carlo simulation of organic light-emitting devices under alternating applied field

Abstract

A Monte Carlo method has been employed to simulate electroluminescence (EL) from organic light-emitting devices (LEDs) under an alternating applied field. EL responses under forward and reverse bias modes have been simulated with different experimental parameters. Dependences of EL on the frequency of an applied field, electrode work function, band gap and film thickness of the active organic material, etc., have been studied. The origin of EL under alternating current (ac) mode has been explained in terms of radiative recombination of excitons formed via injected holes and electrons present from the previous cycle of ac voltage. The time response of EL intensity and its profile during forward and reverse bias half-cycles has been found to depend on carrier injection and also on their temporal and spatial distribution along the thickness of the emitting material. Efforts have been made to match a simulated EL response with representative experimental results. The Monte Carlo simulation results presented here provides a way to select certain parameters to fabricate efficient ac LEDs.