Investigation of large-area OLED devices with various grid geometries

• Excellent agreement of simulation and measurement.
• Demonstration, analysis and measurement of different design approaches for OLED with grid lines.
• Variation of grid element shape is not the best way to find optimal grid structure.
• Variation of grid spacing and grid line width is the best way to optimize grid structure.
• Proof of dependence between different enhancement techniques by simulation.

Luminance homogeneity is an important aspect for large-area (>1 cm2) organic light emitting diodes (OLED). Especially, high sheet resistances of transparent contacts lead to a significant brightness inhomogeneity caused by a drop of local potential difference. Therefore the implementation of thin low-resistance metallic grids onto transparent contacts is a crucial development aspect for large-area OLED design. We develop a finite-element electro-optical simulation for OLED using grid structures to optimize geometry, thickness and width of grid elements. We find an exponential relationship between luminance homogeneity and grid material volume, which leads to limitations of minimal grid line width and maximal emissive area for efficient development of large-area OLED.

(Left) Excellent agreement of simulated and measured luminance distribution. (Right) Two efficient techniques for the enhancement of luminance distribution.Figure optionsDownload as PowerPoint slide