OLED Electrode Sheet Resistance Variation for Brightness Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Organic light-emitting diode structures with transparent electrodes often exhibit non-uniform light distribution, leading to performance issues due to uniform sheet resistance, resulting in hotspots and dim areas.
Innovation Solution
The electrodes are designed with varying sheet resistances by adjusting thickness, adding supplemental conductive or insulating structures, and modifying the electrode material composition, particularly increasing sheet resistance near corners and reducing it in central areas to enhance brightness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform sheet resistance is used in transparent electrodes, then manufacturing is simplified, but light emission uniformity deteriorates causing hotspots and dim areas
Solution Approach 1:
The patent applies local quality by varying the sheet resistance of the transparent electrode across different regions. Specifically, the electrode has higher sheet resistance in peripheral regions and lower sheet resistance in central regions. This spatial variation in electrical properties compensates for non-uniform current distribution, ensuring uniform light emission across the entire electrode area while maintaining manufacturing feasibility through controlled deposition processes.
2Loss of energy
If electrode thickness is increased to reduce ohmic losses, then electrical conductivity improves, but transparency deteriorates
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through spatially varying electrode thickness. The electrode is designed with greater thickness in central regions where current density is highest and ohmic losses are most significant, while maintaining thinner thickness in peripheral regions to preserve transparency. This localized thickness variation optimizes the balance between electrical conductivity and optical transparency in different functional zones of the electrode.
Solution Approach 2:
The patent applies parameter changes by systematically varying the sheet resistance parameter across the electrode surface. Through controlled modification of electrode thickness and/or material composition during fabrication, the sheet resistance is adjusted to achieve optimal current distribution. This parameter variation enables reduction of ohmic losses in high-current-density regions without compromising overall electrode transparency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures more uniform light emission by managing current distribution and reducing ohmic losses, thereby improving the overall brightness and performance of the light-emitting diodes.
Implementation Method 1
portions of the electrodes in a peripheral region of the electrode area may have higher sheet resistances than a central portion of the electrode area
Data Source
AI summary
An organic light-emitting diode may have transparent electrodes. An organic emissive layer may be interposed between the electrodes. The emissive layer may emit light in response to current injected from the electrodes. The organic light-emitting diode electrodes may cover an electrode area. The electrode area may be square or may have other shapes. To enhance brightness uniformity, portions of the electrodes in a peripheral region (H1, H2) of the electrode area may have higher sheet resistances than a central portion of the electrode area. The electrode area may be square and may have four corners. The higher sheet resistances may be associated with regions of the electrode area adjacent to the corners. Elevated sheet resistances may be produced by forming the electrodes with different thicknesses in different areas or by providing supplemental conductive structures (104) in selected areas of the electrode area.