The influence of the optical environment on the shape of the emission profile and methods of its determination

In this paper, we introduce an extension of the coupled electronic-optical model to simulate organic light-emitting devices (OLEDs). We couple the influence of the optical environment to the exciton transport equation which yields a position dependent exciton lifetime. Thereby we get a more accurate spatial distribution of excitons, namely the emission profile. We show that the emission profile is dependent on the intrinsic quantum efficiency. In a second part of this paper, an extended numerical algorithm for extraction of the emission profile from emission spectra is presented. The extended extraction algorithm takes the influence of the optical environment into account. We call it the excitonic lifetime fitting method (ELF) and compare it to a conventional linear fitting method. On the basis of consistency checks we demonstrate the influence of noisy emission spectra and device thicknesses. Our investigations show the impact of the ELF method, which improves the accuracy and robustness of the extracted emission profile considerably up to 120%.