Organic Light Emitting Display Compensation Layer Design
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Solution Overview
Problem
Organic light emitting display devices face defects due to foreign bodies between electrodes, leading to shorts and reduced transmittance, which increases costs and reduces efficiency.
Innovation Solution
Incorporating a compensation layer with a varying composition ratio of compensation materials in the second electrode, allowing for a high resistance area to function as a compensation layer and a low resistance area to act as an electrode layer, preventing shorts and maintaining high transmittance without additional processes or equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick material is spread to prevent short due to foreign body, then reliability is improved, but transmittance is reduced and device complexity increases
Solution Approach 1:
The patent applies local quality by creating a compensation layer with spatially varying composition ratio of compensation material. The composition ratio is higher at locations where foreign bodies are more likely to exist (near the organic light emitting layer) and lower at other locations. This localized concentration of compensation material provides effective short prevention exactly where needed while keeping the cathode thin elsewhere, thus maintaining high transmittance.
Solution Approach 2:
The patent changes the parameter of composition ratio of compensation material within the compensation layer. By varying the composition ratio of compensation material (e.g., oxygen content in IZO or ITO) at different positions, the electrical resistance is locally adjusted. Areas with higher compensation material content have higher resistance, preventing shorts caused by foreign bodies, while the overall layer remains thin to maintain transmittance.
2Reliability
If a compensation layer is added to prevent short, then reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the compensation layer formation with the existing cathode formation process. The compensation layer is formed simultaneously with the cathode in the same vacuum chamber using the same sputtering equipment, by adjusting the composition ratio of compensation material during the deposition process. This integration eliminates the need for separate compensation layer deposition equipment and additional manufacturing steps, reducing device complexity and manufacturing cost while still providing reliable foreign body compensation.
Data Source
AI summary
The present invention relates to an organic light emitting display device. An aspect of the present invention provides an organic light emitting display device comprising a first electrode on a substrate, an organic light emitting layer on the substrate, and a second electrode including at least two layers of which a composition of compensation materials is different on the organic light emitting layer. Another aspect of the present invention provides an organic light emitting display device in which a first electrode includes two or more layers having different compositions of compensation material such that thin and double compensation layers are formed on both surfaces of an organic light emitting layer.