AMOLED Pixel Defining Blocks via Halftone Mask Exposure
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Solution Overview
Problem
Active-matrix organic light-emitting (AMOLED) display screens face issues with uneven illumination due to pinning points during manufacturing, leading to reduced pixel illumination lifetime and stability.
Innovation Solution
A display panel is manufactured using a halftone mask to form pixel defining blocks with a trapezoidal column spacer and hydrophobic organic photoresist bank, allowing for one-time exposure and omitting individual bank formation, ensuring uniform light emission and improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a double-defined column spacer with silicon oxide layer is added to solve uneven illumination, then illumination uniformity is improved, but device complexity and manufacturing process complexity increase
Solution Approach 1:
The patent merges the column spacer and bank formation into a single photoresist coating and exposure process. The photoresist is coated to form a combined structure that serves both as column spacer (in gap regions) and bank (in pixel regions), eliminating the need for separate formation processes and reducing manufacturing complexity while maintaining illumination uniformity
Solution Approach 2:
The photoresist material serves multiple functions: it forms both the column spacer and the bank structure, acts as an organic functional layer, and provides structural support. This multi-functionality reduces the number of materials and processes needed, simplifying the manufacturing process while achieving the desired illumination uniformity
2Illumination intensity
If vapor-depositing silicon oxide layer and yellow-light process are added to remove thicker edge film, then pixel illumination uniformity is improved, but manufacturing time and cost increase
Solution Approach 1:
The patent combines column spacer and bank formation into one photoresist processing step, and integrates the organic functional layer formation within the same photoresist structure. This merging of processes significantly reduces manufacturing time and steps compared to the multi-step vapor deposition and yellow-light processing required in conventional methods
Solution Approach 2:
The patent uses photoresist as a temporary structure that is later removed or serves as the final organic functional layer. This approach avoids the need for permanent inorganic layers like silicon oxide that require additional processing steps, reducing both time and cost
3Illumination intensity
If vapor-depositing silicon oxide layer is added to form double-defined column spacer, then pixel illumination uniformity is improved, but reliability decreases due to electrical effects on thin film transistor
Solution Approach 1:
The patent changes the material parameter from inorganic silicon oxide to organic photoresist. This material substitution eliminates the electrical effects and reliability issues associated with vapor-deposited oxide layers on thin film transistors, while still achieving illumination uniformity through the photoresist-based column spacer and bank structure
Solution Approach 2:
The photoresist serves as a temporary or final organic layer that does not require the same level of long-term stability as inorganic oxide layers. This disposable or transient nature of the photoresist structure avoids the reliability issues associated with permanent inorganic layers that can electrically affect thin film transistors
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 method reduces manufacturing time and cost while achieving uniform light emission and enhancing the stability of the display panel by preventing current flow through defined regions and avoiding hydrogen and oxygen introduction into the thin film transistor.
Implementation Method 1
disposing the halftone mask above the photoresist; irradiating ultraviolet light through the halftone mask to a surface of the photoresist
Implementation Method 2
forming a groove exposed on the surface of the first electrode by dropping a developing solution on the photoresist in the pixel region
Implementation Method 3
material of the pixel defining block comprises hydrophobic organic photoresist
Data Source
AI summary
A display panel and a method of manufacturing thereof are provided. The pixel defining block is formed by one-time exposing the column spacer column and the bank with a halftone mask, thereby omitting the process of individually forming the bank, and manufacturing time and manufacturing cost are reduced. The organic functional layer disposed above the bank is not directly contacted with the first electrode due to the bank structure, and the bank causes the defined region to be disconnected from the first electrode, and no current flows through the defined region. Thus, the defined region does not emit light, and the pixel region emits uniform light. The material of the bank is an organic photoresist, so hydrogen and oxygen are not introduced into the bank, and therefore not affect the thin film transistor, and improves stability of the display panel.