Common Blue OLED Layer Reduces Mask Count
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Solution Overview
Problem
The complexity and cost of manufacturing organic light-emitting devices are increased due to the need for multiple patterned masks, which can lead to misalignment and inefficiencies in the patterning process, particularly when creating sub-pixels for red, green, and blue colors.
Innovation Solution
The use of a common blue light-emitting layer and auxiliary layers with concentration gradients of hole injection and transport materials, which allows for the simplification of the manufacturing process by reducing the number of masks required, and includes a structure where the auxiliary layer is co-deposited with a p-type dopant, aiding in hole transfer across sub-pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple patterned masks are used to create sub-pixels for different colors, then the device can achieve full-color display capability, but the manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent merges the blue light-emitting layer function across all three sub-pixels (R, G, B) into a single common layer that is not patterned. This eliminates the need for separate blue layer patterning masks for each sub-pixel, reducing manufacturing complexity while maintaining full-color display capability through the combination of this common blue layer with separately patterned red and green light-emitting layers
Solution Approach 2:
The common blue light-emitting layer serves a universal function across all sub-pixels, providing the blue emission component for R, G, and B sub-pixels simultaneously. This multi-functional approach allows a single unpatterned layer to fulfill what would traditionally require multiple patterned layers, simplifying the manufacturing process
2Manufacturing precision
If multiple patterned masks are used for sub-pixel patterning, then color accuracy can be achieved, but misalignment and shadow phenomena occur during deposition
Solution Approach 1:
The patent extracts the blue light-emitting layer patterning requirement from the multi-mask process by making it a common unpatterned layer. This removes the source of potential misalignment between blue layer patterns and other color layers, improving patterning alignment reliability while color accuracy is maintained through the selective patterning of red and green layers
Solution Approach 2:
Instead of patterning all three color layers (R, G, B) separately to achieve color accuracy, the patent inverts the approach by leaving the blue layer unpatterned and common to all sub-pixels, while only patterning the red and green layers. This reduces the number of patterning operations and minimizes cumulative alignment errors
3Manufacturing precision
If multiple patterned masks are used in the manufacturing process, then sub-pixel definition can be achieved, but the number of manufacturing steps and cost increase
Solution Approach 1:
The patent merges the blue light-emitting layer deposition step across all sub-pixels into a single unpatterned deposition process. This reduces the total number of patterning and deposition steps required, improving manufacturing efficiency and productivity while sub-pixel definition is maintained through the selective patterning of red and green light-emitting layers
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 maintains high luminous efficiency while simplifying the device structure and manufacturing process, reducing the number of masks needed and minimizing shadow phenomena during deposition, thereby improving the reliability and cost-effectiveness of the organic light-emitting device.
Implementation Method 1
the auxiliary layer may have a concentration gradient in which a concentration of the hole injection material is greater than a concentration of the hole transport material in a lower portion of the auxiliary layer, and in which a concentration of the hole transport material is greater than a concentration of the hole injection material in an upper portion of the auxiliary layer
Implementation Method 2
a co-deposited layer of a hole injection material and a hole transport material
Implementation Method 3
When an electron and a hole are recombined at a certain molecule, a molecular exciton having a high-energy excited state is formed. Light inherent to a material is emitted as the molecular exciton returns to a low-energy ground state
Data Source
AI summary
Provided is an organic light-emitting device including a plurality of pixels, each including a first sub-pixel, a second sub-pixel, and a third sub-pixel having different colors from each other. Each of the pixels includes a substrate, a first electrode layer on the substrate, a first light-emitting layer disposed on the first electrode in the first, second and third sub-pixels, an auxiliary layer disposed on the first light-emitting layer in the second and third sub-pixels, a second light-emitting layer disposed on the auxiliary layer in the second sub-pixel, a third light-emitting layer disposed on the auxiliary layer in the third sub-pixel, and a second electrode layer on the first, second, and third light-emitting layers.