Light Emitting Element Ink Viscosity Control via Hydrogen Bonding
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Solution Overview
Problem
Existing light emitting element inks face issues with precipitation during storage, leading to inconsistent dispersion and reduced product reliability in display devices, as they are prone to settling due to gravity differences, affecting the uniformity of light emitting elements in the ink.
Innovation Solution
A light emitting element ink is developed with a thickener that forms hydrogen bonds, adjusting viscosity from 30 cP to 300 cP in storage to prevent precipitation, and to 5 cP to 15 cP during printing, ensuring uniform dispersion and easy nozzle flow, using a compound represented by Chemical Formula 1, and including a dispersant for improved dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light emitting element ink is stored without a thickener, then the ink has low viscosity and flows easily during printing, but the light emitting elements precipitate during storage due to gravity differences
Solution Approach 1:
The patent applies a thickener that dynamically adjusts the ink's viscosity based on shear stress conditions. During storage (no shear stress), the thickener maintains high viscosity to prevent precipitation. During printing (shear stress applied), the viscosity decreases to enable easy flow and nozzle discharge. This dynamic viscosity adjustment resolves the contradiction between storage stability and printability.
Solution Approach 2:
The patent changes the viscosity parameter of the ink by introducing a thickener that responds to shear stress. The viscosity transitions from a high state during storage to a low state during printing, allowing the ink to satisfy both storage stability requirements and printing performance requirements through parameter transformation.
2Reliability
If a thickener is added to prevent precipitation, then storage stability improves, but the ink viscosity increases making it difficult to flow through nozzles during printing
Solution Approach 1:
The thickener used in the patent exhibits dynamic viscosity characteristics where viscosity changes in response to shear stress. During storage with no shear stress, viscosity remains high for stability. During printing when shear stress is applied through nozzle flow, viscosity decreases to improve flowability and printing efficiency, thus resolving the contradiction between storage stability and printing productivity.
Solution Approach 2:
The ink experiences periodic transitions between high-viscosity storage state and low-viscosity printing state. The thickener enables this periodic action by maintaining high viscosity during storage periods and reducing viscosity during printing periods when shear stress is applied, allowing the system to alternate between stability and productivity modes.
3Productivity
If the ink viscosity is kept low for easy printing, then printing efficiency improves, but light emitting elements settle and disperse uniformly during storage
Solution Approach 1:
The patent uses a dynamic viscosity adjustment mechanism through the thickener to resolve the contradiction between printing efficiency and dispersion uniformity. During storage (low shear stress), high viscosity maintains uniform dispersion and prevents settling. During printing (high shear stress), low viscosity enables efficient nozzle flow and discharge, achieving both uniformity and efficiency at different stages.
4Ease of manufacture
If no thickener is used in the ink, then the manufacturing process is simpler, but foreign matter and precipitated elements cannot be completely removed affecting product reliability
Solution Approach 1:
The patent introduces a thickener that changes the viscosity parameter of the ink to resolve the contradiction between manufacturing simplicity and product reliability. The thickener enables high viscosity during storage to prevent precipitation, allowing complete removal of foreign matter and precipitated elements through filtration, thereby improving product reliability while maintaining relatively simple manufacturing processes.
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 ink maintains light emitting elements in a dispersed state for long periods, ensures uniform distribution during printing, and allows for complete removal of solvent and thickener, enhancing product reliability by preventing clogging and ensuring consistent alignment of light emitting elements.
Implementation Method 1
a compound of the thickener includes a functional group capable of forming a hydrogen bond together with a compound of the light emitting element solvent or another compound of the thickener
Implementation Method 2
In a state in which shear stress is applied to the light emitting element ink, the compound of the thickener may not form an intermolecular hydrogen bond together with the compound of the light emitting element solvent and the other compound of the thickener, and the light emitting element ink may have a viscosity in a range of from 5 cP to 15 cP
Implementation Method 3
forming an electric field on the target substrate to place the light emitting elements on the first electrode and the second electrode
Implementation Method 4
treating the light emitting element ink under a low-pressure environment to remove the light element solvent and the thickener
Data Source
AI summary
A light emitting element ink and a method of manufacturing a display device are provided. The light emitting element ink includes a light emitting element solvent, a light emitting element dispersed in the light emitting element solvent, the light emitting element including a plurality of semiconductor layers and an insulating film surrounding outer surfaces of the semiconductor layers, a thickener dispersed in the light emitting element solvent, wherein a compound of the thickener includes a functional group capable of forming a hydrogen bond together with a compound of the light emitting element solvent or another compound of the thickener and the compound of the thickener is represented by Chemical Formula 1.