Nonlinear electro-thermal modeling and field-simulation of OLEDs for lighting applications I: Algorithmic fundamentals

Large area OLEDs aimed at lighting applications should provide homogeneous luminance—homogeneity is one of the quality metrics of such devices. Local light generation depends on both the local temperature and the local voltage drop across the light emitting polymer(s) in the device. Therefore the thermal and electrical engineering of OLEDs aimed at lighting applications is critical. Due to the large area of these devices the coupled electrical and the thermal simulation problem is of distributed nature. Electrical characteristics of organic semiconductor materials used in OLED devices are highly nonlinear, and their nonlinear temperature-dependence is significant. In our present approach to distributed electro-thermal field simulation we address special needs of OLEDs, which is not yet the case with widely used, commercially available simulation tools. In this paper we present the latest version of our SUNRED electro-thermal field solver algorithm capable of handling coupled, non-linear electro-thermal problems. The new features of the algorithm are demonstrated by modeling some research OLED samples available to us in the Fast2Light project—this way simulation results are compared against measured data.

► Electro-thermal characteristics of OLEDs are described by power function.
► OLED characteristics are applied in FDM based field solver.
► The solver can provide temperature, voltage, current and heat flux maps.
► Any nonlinear function can be applied as pn junction.
► Simulation results are validated by measurement results of different sized OLEDs.