Detailed analysis of exciton decay time change in organic light‐emitting devices caused by optical effects

Abstract

Abstract— The exciton decay time in organic light‐emitting devices (OLEDs) depends on the optical environment, i.e., the thicknesses and refractive indices of all layers in a device. The decay of an exciton can occur through a radiative or a non‐radiative channel. Each of these channels has a probability, which is expressed by, respectively, the radiative and the non‐radiative decay rate. The radiative decay rate is influenced by the optical environment, i.e., the OLED's thin‐film layer structure. In this paper, a model for estimating the change of the exciton decay time (inverse of the decay rate) is presented. In addition, the decay time change in both top‐ and bottom‐emitting OLEDs as a function of the charge‐transport layer thicknesses has been investigated. Furthermore, the most important mechanism responsible for the exciton decay time change is outlined.