OLED Pixel Unit Electrode Area Compensation for Color Shift
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Solution Overview
Problem
Organic Light-Emitting Diode (OLED) display panels experience color shift due to varying emission lifespans of sub-pixel units, which is exacerbated by different attenuation rates of emission layers over time, leading to inefficiencies in manufacturing and reduced display lifespan.
Innovation Solution
A pixel unit design where sub-pixel units have emission layers with different lifespans, with the area of the emission layer closer to the substrate being equal across units, and the first electrode's area varying to match the emission lifespan, ensuring uniform drying conditions and balanced current density, thereby minimizing color shift and extending display lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If emission layers of different sub-pixel units are manufactured separately to account for different attenuation rates, then color shift is reduced, but manufacturing time and complexity increase
Solution Approach 1:
The patent applies local quality by making the first electrode area different for different sub-pixel units while keeping the emission layer area uniform. Specifically, sub-pixel units with faster attenuating emission layers have larger first electrode areas, allowing them to receive higher current density. This local variation in electrode area compensates for the different attenuation rates without requiring separate manufacturing processes, thus resolving the contradiction between display lifespan and manufacturing time
2Productivity
If emission layers of different sub-pixel units are manufactured simultaneously with equal drying conditions, then manufacturing efficiency improves, but color shift occurs due to different attenuation rates
Solution Approach 1:
The patent changes the parameter of first electrode area to compensate for different emission layer attenuation rates. By adjusting the first electrode area according to the specific emission layer characteristics of each sub-pixel unit, the patent enables simultaneous manufacturing with uniform drying conditions while maintaining balanced current density and reducing color shift, thus resolving the contradiction between manufacturing efficiency and display lifespan
3Ease of manufacture
If current density is uniformly distributed across all sub-pixel units, then manufacturing is simplified, but emission layers with different lifespans experience unbalanced stress leading to color shift
Solution Approach 1:
The patent introduces asymmetry by making the first electrode areas different for different sub-pixel units based on their emission layer characteristics. This asymmetric design allows the patent to achieve balanced current density distribution across sub-pixel units with different emission layer lifespans, thereby improving color stability while maintaining manufacturing simplicity through a unified manufacturing process
Data Source
AI summary
A pixel unit, a display panel, a display device and a method of manufacturing a pixel unit. The pixel unit includes a first sub-pixel unit and a second sub-pixel unit, each sub-pixel unit includes a first electrode, an emission layer, and a second electrode stacked on a substrate. An emission lifespan of the emission layer of the first sub-pixel unit is smaller than that of the emission layer of the second sub-pixel unit. An area of an orthographic projection of the emission layer of the first sub-pixel unit on the substrate is equal to that of the emission layer of the second sub-pixel unit on the substrate. An area of an orthographic projection of the first electrode of the first sub-pixel unit on the substrate is greater than an area of an orthographic projection of the first electrode of the second sub-pixel unit on the substrate.