AMaSiS 2018 Workshop: Abstracts

A parameterization for the current-voltage-temperature relation of organic light-emitting diodes for p-Laplace-based large area device simulation

Axel Fischer${}^{\mathbf{\text{(1)}}}$, Matthias Liero${}^{\mathbf{\text{(2)}}}$, Annegret Glitzky${}^{\mathbf{\text{(2)}}}$, Jürgen Fuhrmann${}^{\mathbf{\text{(2)}}}$,

and Sebastian Reineke${}^{\mathbf{\text{(1)}}}$

(1) Dresden Integrated Center for Applied Physics and Photonic Materials

[0.2em] (2) Weierstrass Institute for Applied Analysis and Stochastics, Berlin

Organic light-emitting diodes (OLEDs) are thin film devices which can be processed on large areas (e.g. $>$100 cm${}^2$). In order to simulate the device behavior, one has to assume that the local current density as well as the local temperature can change a lot. Especially, due to the strong temperature activated electrical conductivity, Joule self-heating causes strong inhomogeneities in device operation [1]. Thus, a model which can describe the local current-voltage (jV) characteristic within a large range of current densities and application relevant temperatures is highly appreciated.

Here, we introduce an equivalent circuit model which is able to do so by representing the OLED as a combination of thermistors which either have power-law character or exponential-law character of the jV-curves due to charge carrier transport or recombination, respectively [2]. Because of the excellent agreement with isothermal experimental data, the model is then able to correctly predict the occurrence of nonlinear self-heating effects including jV-regimes of negative differential resistance.

The strength of our approach relies in the parameterization which can be transferred to a p-Laplace based system of partial differential equations which then can be used to simulate the device behavior over large areas for arbitrary shape and structure [3]. Additionally, the material related parameters gained by fitting experimental data can directly be used. Together with a robust solver which is able to handle the negative differential resistance of the device, advanced self-heating effects such as regions of switched-back current density or tri-stable switching behavior can be modeled.

Acknowledgments: This work was supported in part by the German Research Foundation (DFG) within the Cluster of Excellence Center for Advancing Electronics Dresden (cfaed), the DFG project “Electrothermal feedback in organic devices” (EFOD, RE 3198/6-1), and by Einstein Foundation Berlin in the MATHEON project SE18.