Abstract
Typically, organic light-emitting diodes (OLEDs) are characterized only in steady-state to determine and optimize their efficiency. Adding further electro-optical measurement techniques in frequency and time domain helps to analyze charge carrier and exciton dynamics and provides deeper insights into the device physics. We, therefore, first present an overview of frequently used OLED measurement techniques and analytical models. A multilayer OLED with a sky-blue thermally activated delayed fluorescent dopant material is employed in this study without loss of generality. Combining the measurements with a full device simulation allows one to determine specific material parameters such as the charge carrier mobilities of all the layers. The main part of this tutorial focuses on how to systematically fit the measured OLED characteristics with microscopic device simulations based on a charge drift-diffusion and exciton migration model in 1D. Finally, we analyze the correlation and sensitivity of the determined material parameters and use the obtained device model to understand limitations of the specific OLED device.
Highlights
The newest display technologies could not be realized without developments in organic light-emitting diodes (OLEDs)
Besides the traditional solution or film characterization techniques, such as cyclic voltammetry[2,3,4] and ultraviolet photoelectron spectroscopy (UPS),[5] new materials need to be thoroughly characterized in full multilayer OLED devices or specific layer stacks to assess their suitability in real applications
We presented a set of advanced DC, AC, and transient electro-optical measurement techniques for OLEDs that can be carried out with a single measurement system,[23] achieving highly consistent data for modeling by avoiding re-contacting the device in distinct sample holders of different setups
Summary
The newest display technologies could not be realized without developments in organic light-emitting diodes (OLEDs). The preferred way to determine material parameters in complete OLED devices is, to combine numerical simulations with experimental data Often, these comparisons were solely focusing on steady-state analysis.[14,15,16] In such cases, care has to be taken about the correlation between and the sensitivity to the analyzed material parameters.[17,18,19] In order to increase the reliability of device simulation, it is inevitable to include complementary measurement techniques in time and/or frequency domain.[19,20,21]. We demonstrate how the simulation can further be used to analyze device characteristics and how possible routes for efficiency improvements can be identified based on these findings
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