DESIGN AND OPTIMIZATION OF LARGE-AREA OLEDS BY ELECTRO-THERMAL MODELING S. Altazin 1, R. Hiestand 1, C. Kirsch 2, M. Diethelm 1,2, L. Penninck 1, M. A. Maindin 1, M. Fontenlos 1, B. Ruhstaller 1,2* beat.ruhstaller@zhaw.ch 1 Fluxim AG, Technoparkstrasse 2, 8406 Winterthur, SWITZERLAND, 2 Zurich University of Applied Sciences, Institute of Computational Physics, Technikumstrasse 9, CH-8401 Winterthur, SWITZERLAND TADF OLED Summer School, May 23, 2017 Krutyn, Poland
Content Talk 4 Motivation for large-area simulation of OLEDs and FEM intro OLED lighting panel validation example AMOLED pixel cross-talk Laoss software 2
Our Product Family Easy-to-use simulation software setfos able to simulate OLEDs and thin film PVs on the small scale/cell level. Easy-to-use all-in-one characterization platform paios to extract device and material parameters by dynamic characterization. Easy-to-use large-area simulation software laoss able to simulate OLEDs and solar cells up to the module scale. laoss
From Small to Large OLEDs Lab OLED Source: wikipedia.org/wiki/oled Large-area OLED 2x2 mm 2 1D model sufficient Optimization: o Ageing o Transport (charge carrier balance) o Light outcoupling Source: spie.org/x23960.xml >10x5 cm 2 3D model necessary Optimization: Brightness inhomogeneity Sheet resistivity Thermal management
Design challenges (OLEDs) Improve conductivity in transparent electrodes while transparency remains high Large currents at moderate voltages, steep j(v) curves => resistive losses have strong influence on working point and thus brightness Steep j(v) curve, especially due to doped layers
Laoss: Design of large-area panels
OLED Panels w/ Light Extraction & Metal Grid LG Chem Example Angular Luminous Intensity - With scatter foil - Without x 2.1 External scatter foil Metal grid to enhance electrical electrode conductivity and thus uniformity
Feel the heat (OLED lighting) Measured OLED panel «Tabola» (Fraunhofer Commedd) temperature and luminance distribution at 1 A Temperature Luminance A. Fischer et al. 2013, WIAS Berlin
OLED Panel Example Without (left) and with (right) metal grid 10 cm x 10 cm OLED panel at 6 volts Neyts et al., J. App. phys. 100, 114513 (2006)
LAOSS Simulation Examples: Electrode potential distribution 2D Potential profile With grid Without grid
FEM Simulation of OLED Panel Comparison between 1D model and 2D+1D simulations 1D analytical Mott-Gurney law 2D+1D model for a large area electrode 2D+1D model including highly conductive stripes (1D aluminum grid). 15*15 cm 2 ITO Al 2D+1D model including highly conductive stripes (2D aluminum grid). 2D+1D model is successfully applied to study the effect of conductivity enhancement in OLED panel 13
Content Talk 4 Motivation for large-area simulation of OLEDs OLED lighting panel validation example AMOLED pixel cross-talk Laoss software 14
AMOLED Pixel Cross Talk Laoss simulation of cross talk in an AMOLED display with common HTL layer Inspiration: Influence of Lateral Current Caused by Hole Injection Layer in the AMOLED Kwon, Kim, Choi and Kwon, presented at IMID 2016, Jeju Island, South Korea Confidential
AMOLED Pixel Cross Talk Geometry Schematic layout & derived dimensions Laoss model Microscope picture Confidential
AMOLED Pixel Cross Talk Parameters 1. blue pixel 1. red pixel 1. green pixel Applied voltage Confidential
AMOLED Pixel Cross Talk Results Voltage in HTL Current density in pixels Adressed pixel Cross talk pixel
AMOLED Pixel Cross Talk Results Confidential
Content Talk 4 Motivation for large-area simulation of OLEDs and FEM intro OLED lighting panel validation example AMOLED pixel cross-talk Laoss software 20
Laoss: Benefits Exploit FEM simulations without being a specialist State-of-the-art FEM code & calculation speed Easy-to-use, get started quickly Choose between pre-defined, parametrized layouts or CAD file import for advanced geometries Parameter sweeps with post-processing (J(V) curves, profiles, power dissipation)
LAOSS: FEM Method We do a 2D+1D coupling instead of 3D: - import a 1D IV curve (from a small device) - and solve Ohm s law in the large 2D anode by FEM. 2D FEM 1D coupling law Calculates Electric potential distribution 2D FEM : Input quantities : Output quantities IV curve of the module
Simulation Workflow with Laoss Run meshing Draw and import the device geometry (.dxf file) Import local IV curve & enter electrode conductivity Alternative: Parametrized, pre-defined layouts Run the simulation
Pre-defined Layouts
CAD Drawing Software Follow some Laoss conventions, use (any) CAD software to draw layouts, define and name subdomains («blocks»), save to.dxf file. www.librecad.org
Basic Operation Geometry definition Vertical coupling Result analysis
LAOSS Model Choice Coupled Electrode (solves both domains) Single Electrode (solves 1 domain only) Top electrode Bottom electrode Bottom electrode at 0 V 29
Post-processing (1): Profiles
Post-processing (2): jv curves
Conclusions We introduced a new tool LAOSS for the simulation of solar cells & modules and OLEDs It allows to simulate solar modules and OLEDs in order to maximize the power efficiency by tuning the electrode materials and geometry laoss