Double-Layer Pixel Definition Structure for OLED Undercut Prevention
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Solution Overview
Problem
Conventional pixel definition layers in OLED display devices are prone to undercut, affecting the stability and efficiency of the quantum dot light-conversion layer, particularly in blue light-conversion processes.
Innovation Solution
A color filter substrate with a double-layer pixel definition structure, comprising a first pixel-defining structure made of silicon oxide, silicon nitride, or organic materials and a second pixel-defining structure of light-shielding hydrophobic materials, which provides enhanced structural support and prevents undercut, allowing for a higher height and improved stability of the quantum dot light-conversion layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer pixel definition layer is used, then the fabrication process is simple, but the layer is prone to undercut and cannot meet the height required for inkjet printing
Solution Approach 1:
The pixel definition layer is divided into two distinct layers: a first pixel definition layer (PDL1) made of inorganic material (silicon oxide or silicon nitride) and a second pixel definition layer (PDL2) made of organic material. This segmentation allows each layer to fulfill specific functions - PDL1 provides structural support and height while PDL2 provides hydrophobicity and pattern definition, thereby preventing undercut and meeting inkjet printing height requirements without excessive complexity
Solution Approach 2:
The invention uses composite material structure where PDL1 is formed from inorganic materials (silicon oxide or silicon nitride) and PDL2 is formed from organic materials. This composite approach combines the advantages of both material types - the structural stability and height capability of inorganic materials with the hydrophobicity and ease of patterning of organic materials, effectively preventing undercut phenomenon
2Length of stationary object
If the pixel definition layer height is increased to meet inkjet printing requirements, then the quantum dot light-conversion layer stability is improved, but the layer becomes more prone to undercut
Solution Approach 1:
By segmenting the pixel definition layer into PDL1 (inorganic, provides height and structural support) and PDL2 (organic, provides hydrophobicity), the invention achieves the required height for inkjet printing while preventing undercut that would compromise quantum dot light-conversion layer stability
Solution Approach 2:
Different regions of the pixel definition structure are assigned different materials with specific local properties: PDL1 uses inorganic materials for structural integrity and height, while PDL2 uses organic materials for hydrophobicity and pattern definition. This local quality differentiation ensures both height requirements and undercut prevention are met simultaneously
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
The double-layer structure enhances the stability of the quantum dot light-conversion layer, improves blue light-conversion efficiency, and reduces the occurrence of undercut, thereby increasing product yield and maintaining shading properties.
Implementation Method 1
the second pixel-defining structure encapsulates the first pixel-defining structure
Implementation Method 2
a material used for the second pixel-defining structure is a light-shielding hydrophobic material
Implementation Method 3
quantum dot (QD) material itself has excellent properties of high color purity and continuous spectral adjustments, making it the most excellent luminescent material
Data Source
AI summary
A color filter substrate and a fabricating method thereof are provided. The color filter substrate has a pixel definition layer having a first pixel-defining structure and a second pixel-defining structure, and the second pixel-defining structure encapsulates the first pixel-defining structure. The pixel definition layer enhances its structural support strength while ensuring its own shading property and hydrophobicity, so that it can reach a target height, and an undercut phenomenon is less likely to occur.