Display Substrate Pixel Defining Layer Contact Angle Uniformity
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Solution Overview
Problem
Existing display substrates face challenges in achieving uniform film layer formation due to differences in evaporation rates and solvent atmospheres between edge and central regions of pixel areas, leading to non-uniform morphologies in OLEDs during the solution processing method, particularly in large-size applications.
Innovation Solution
A display substrate with a pixel defining layer having different contact angles for long and short sides, where the contact angle for long sides is larger than for short sides, allowing for varying hydrophobicity to control the flow of compensation liquid, thereby ensuring faster flow in the long side direction and slower flow in the short side direction, which improves the uniformity of the film layer formed by ink droplets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the pixel defining layer uses uniform material properties, then the manufacturing process is simple, but the film layer formation becomes non-uniform due to different evaporation rates at edge and central regions
Solution Approach 1:
The pixel defining layer is designed with spatially varying contact angles: the long sides have a first contact angle (40°-50°) while the short sides have a second contact angle (50°-60°). This local differentiation compensates for the non-uniform evaporation rates across the pixel region, enabling uniform film layer formation despite the simplicity of using a single material composition throughout the layer
Solution Approach 2:
The contact angle parameter of the pixel defining layer material is specifically optimized to create different wettability characteristics at long and short sides. By controlling the contact angle values (first contact angle 40°-50°, second contact angle 50°-60°), the system achieves uniform capillary flow compensation across the pixel region, resolving the contradiction between manufacturing simplicity and film uniformity
2Reliability
If the contact angle is increased for better hydrophobicity control, then the liquid flow resistance increases, but the film layer uniformity may be compromised due to excessive flow restriction
Solution Approach 1:
The contact angle parameters are precisely optimized within specific ranges (long sides: 40°-50°, short sides: 50°-60°) to achieve the right balance between flow resistance and film uniformity. These parameter values provide sufficient hydrophobicity control while preventing excessive flow restriction that would compromise film layer quality
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 enhances the uniformity of the film layer by creating different resistances for the compensation liquid, resulting in improved film formation and reducing morphological differences between long and short sides, thus addressing the non-uniformity issues in existing substrates.
Implementation Method 1
a contact angle of a material for defining the long sides of the pixel regions of the pixel defining layer is larger than a contact angle of a material for defining the short sides of the pixel regions of the pixel defining layer
Data Source
AI summary
The disclosure relates to a display substrate, a preparation method of the display substrate and a display device. A contact angle of a material, for defining long sides of pixel regions, of a pixel defining layer is larger than a contact angle of a material, for defining short sides of the pixel regions, of the pixel defining layer.