Pixel Define Layer Formation via Three-Section Photomask Exposure
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Solution Overview
Problem
Organic light-emitting display devices face issues with antireflection and the lack of a suitable replacement for polarizing films, particularly in flexible devices, leading to problems like pixel shrinkage, dark spots, and reduced lifespan due to complex manufacturing processes involving multiple layers and high-temperature curing.
Innovation Solution
A method is developed to integrate the formation of two layers into a single process using a photosensitive resin composition with a photomask transmittance divided into three sections, allowing for controlled curing and reduced process time, which includes applying and coating the resin, prebaking, exposure, development, and post-heat treatment, with specific conditions for irradiation and temperature to minimize damage and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple support layers are formed to increase structural stability, then the display device achieves better mechanical strength, but the process time increases and panel damage occurs due to multiple coating, exposure, development, and heat curing steps
Solution Approach 1:
The patent combines the formation of the support layer and color filter layer into a single integrated layer formed through one photolithography process. This merging eliminates the need for separate coating, exposure, development, and heat curing steps for each layer, thereby reducing process time and minimizing panel damage while maintaining the structural stability provided by multiple functional layers
2Strength
If multiple support layers are formed to increase structural stability, then the display device achieves better mechanical strength, but panel damage occurs due to multiple coating, exposure, development, and heat curing steps
Solution Approach 1:
The patent merges the support layer and color filter layer formation into a single integrated process step. By forming both layers simultaneously through one photolithography sequence, the number of repeated coating, exposure, development, and heat curing cycles is reduced, thereby minimizing cumulative panel damage from outgassing, thermal stress, and mechanical handling while preserving the structural benefits of multiple functional layers
3Productivity
If photomask transmittance is divided into three sections with varying irradiation amounts, then two layers are formed in one process with controlled curing, but the exposure process becomes more complex
Solution Approach 1:
The patent applies local quality by using a photomask with three distinct transmittance sections (0%, 20-50%, and 100%) that selectively control the irradiation amount to different regions of the photosensitive resin composition. This enables different curing degrees in different areas, allowing simultaneous formation of support layer and color filter layer with different thicknesses and properties in a single exposure process, thereby achieving process integration without requiring multiple exposure steps
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 vivid colors, increases display reliability, and extends the lifespan of organic light-emitting displays by reducing process time and minimizing damage, while maintaining luminance and preventing pixel shrinkage.
Implementation Method 1
performing exposure; performing post-exposure
Implementation Method 2
performing exposure; performing post-exposure; performing post-heat treatment
Data Source
AI summary
Provided is a method for preparing a pixel defining layer, which is not only to ensure vivid colors, but also to increase display reliability and lifespan by creating one or more layers through one-time process of performing coating, prebaking, exposure, development, post-exposure, and post-heat treatment and thus implementing a colored pattern capable of reducing the process time on the electrode substrate, wherein the method unifies the processes of two layers of the PDL and CS layers of the organic light emitting diode panel into one by including the colorant according to the present disclosure, and shortens the process time by adjusting the UV active ray transmittance of the photomask to three sections of 0% (non-exposed portion), 20 to 50% (Half-tone), and 100% (Full-tone) in order to create a step height in the pattern after the development process is completed and thus forming two layers at once.