Optical simulations of organic light-emitting diodes with non-uniform layers based on two-step domain decomposition method

Abstract

Non-uniform layers are a common and unavoidable phenomenon in the fabrication of pixel organic light-emitting diodes (OLEDs), particularly in inkjet printing (IJP), which often exhibits pronounced coffee-ring effects. However, accurately simulating these non-uniform features in pixel OLEDs remains a significant challenge for existing methods. In this work, a two-step domain decomposition method was proposed to accurately and efficiently analyze pixel OLEDs with non-uniform layers. In the first step, the whole pixel was divided into several non-overlapping regions according to the dipole radiation range, and the classical dipole radiation model combined with the scattering-matrix method was applied. In the second step, each radiation region was subdivided into uniform and non-uniform parts (quasi-uniform parts), and a modified physical model was introduced to correct the reflection coefficient, transmission coefficient, and phase difference caused by non-uniform layers. The proposed method was verified through both numerical simulations and experiments on a typical IJP OLED. The results showed excellent agreement between the simulated and experimental data, with computational efficiency improved by a factor of 182 compared with COMSOL Multiphysics®. In addition, the analysis of the Purcell effect of a single dipole in a truncated Gaussian microcavity revealed the influence of non-uniformity on the microcavity effect. It explains the physical mechanism of the optical effect caused by non-uniformity, providing a theoretical fundament for non-uniform OLED optimization and manufacturing. This method breaks through the limitations of the traditional uniform model and facilitates the optical simulation and analysis of large-area pixel OLEDs with non-uniform layers.

Graphical abstract

Keywords

organic light emitting diode / two-step domain decomposition method / non-uniform layer / optical simulation

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