Light Emitting Element Ink With Temperature-Responsive Dispersion Control
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Solution Overview
Problem
Existing display device manufacturing processes face challenges in storing light emitting elements in a dispersed state for long periods and ensuring complete removal of foreign matter post-printing to improve product reliability.
Innovation Solution
A light emitting element ink is developed, comprising a solvent, dispersed light emitting elements with semiconductor layers and an insulating film, and a thickener that forms hydrogen bonds to adjust viscosity with temperature. This ink is used in a method that includes ejecting the ink onto a target substrate, forming an electric field to align the elements, and heat-treating under low-pressure to remove the solvent and thickener.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a light emitting element ink is stored at room temperature, then the light emitting elements may settle or aggregate over time, but increasing the viscosity to prevent settling may cause printing difficulties and require higher printing temperatures
Solution Approach 1:
The patent uses temperature-responsive viscosity change to resolve the contradiction. The ink is designed to have high viscosity at room temperature for stable storage and low viscosity at elevated temperatures for easy printing. This parameter change with temperature allows the same ink to exhibit different flow characteristics under different conditions, satisfying both storage stability and printing processability requirements.
Solution Approach 2:
The ink's viscosity is made dynamic rather than static by incorporating temperature-responsive thickening agents. The viscosity automatically adjusts based on temperature: remaining high during storage to prevent settling, then decreasing during printing when heated to improve flow and ejectability. This dynamic property allows the ink to adapt to different process stages.
2Ease of manufacture
If the ink viscosity is reduced to improve printing processability, then printing becomes easier, but the light emitting elements may aggregate or settle during storage
Solution Approach 1:
The patent employs temperature-dependent viscosity modification where the thickening agents remain inactive at printing temperatures, allowing low viscosity for easy printing. Upon cooling to storage temperature, the thickening agents activate and increase viscosity to prevent aggregation, thus resolving the contradiction between printing ease and storage stability.
Solution Approach 2:
The ink formulation includes temperature-responsive polymers that dynamically adjust viscosity based on thermal conditions. During printing, the ink is heated to suppress thickening agent activity, ensuring low viscosity and good processability. After printing, the ink cools and the thickening agents activate to increase viscosity and stabilize the dispersion.
3Reliability
If foreign matter is not completely removed after printing, then product reliability decreases, but implementing additional removal steps increases manufacturing complexity
Solution Approach 1:
The patent extracts and removes the thickening agents from the ink after the printing process through a removal step. This extraction eliminates the source of potential foreign matter contamination while maintaining the simplicity of the overall process. The thickening agents are specifically designed to be removable after serving their purpose during storage and printing.
Solution Approach 2:
The thickening agents are designed to be easily removable after printing, preparing the ink for complete removal in a subsequent step. This preliminary design of the thickening agent structure enables simple removal processes, avoiding the need for complex removal procedures and reducing manufacturing complexity while ensuring high product reliability.
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 extended periods due to temperature-dependent viscosity, and the method ensures complete removal of foreign matter, enhancing product reliability and uniformity.
Implementation Method 1
the thickener may include a compound represented by Chemical Structural Formula 1 below as a polyol-based compound capable of forming a hydrogen bond with the light emitting element solvent or another thickener
Implementation Method 2
heating the light emitting element ink under a low-pressure environment to remove the light emitting element solvent and the thickener
Data Source
AI summary
A light emitting element ink comprises 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 plurality of semiconductor layers, and a thickener dispersed in the light emitting element solvent, wherein the thickener includes a compound represented by Chemical Structural Formula 1 as a polyol-based compound capable of forming a hydrogen bond with the light emitting element solvent or another thickener, and the thickener has a boiling point in a range of about 200° C. to about 450° C.