Date

Place

[56-2]
15:55 ~ 16:10
Title:Combining Simulations and Experiments to Study the Impact of Polar OLED Materials
Stephane?Altazin (Fluxim AG, Switzerland), Simon?Zufle (ZHAW, Switzerland), Lieven?Penninck, and Beat?Ruhstaller (Fluxim AG, Switzerland)
Abstract: ETL (Electron Transport Layers) materials often have a non-zero molecular dipole moment. When deposited in an OLED device, this results in a layer with a positive sheet charge density on one side and a negative on the other. So far, only experimental studies have been performed to study the impact of the polarity on the device operation. For the first time we study the effect of polar ETL materials by both electrical characterizations and numerical drift-diffusion simulations using SETFOS 4.1. Previous studies of Brutting et al. have shown that the polar nature of Alq3 and other polar organic materials induces a typical signature in the capacitance?voltage experiment. Indeed, as we can observe in Fig. 1, two plateaus can be observed in the C-V characterization. Interestingly, the transition voltage (Vtr) at which the capacitance changes is strongly dependent on the thickness of the Alq3 layer. It can be noticed that C-V simulations of such devices, performed with SETFOS 4.1, can reproduce the experimental observation. The validity of our model is also confirmed by low temperature (221-314K) measurements of the capacitance versus frequency of these OLEDs using PAIOS 2.0.
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