Ink Composition for Organic Light Emitting Device Film Flatness
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Solution Overview
Problem
The existing inkjet process for organic light emitting devices faces challenges in forming smooth and flat films due to poor solvent selection, leading to issues like precipitation and surface roughness, as current solvents either fail to maintain discharge stability or result in clogged nozzles.
Innovation Solution
An ink composition incorporating a compound represented by Chemical Formula 1 and a solvent, along with a p-type doping material, is used, which includes a compound that can be crosslinked by heat or light, and a glycol ether-based solvent with a high boiling point to ensure stable film formation and prevent nozzle clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solvent with a high boiling point is used to maintain discharge stability, then nozzle clogging is prevented, but film flatness and surface smoothness deteriorate due to poor solubility and precipitation
Solution Approach 1:
The patent changes the chemical parameters of the solvent system by selecting specific glycol ether-based solvents (diethylene glycol dibutyl ether, diethylene glycol diph enyl ether, or dipropylene glycol monophenyl ether) with controlled boiling points and solubility characteristics. This parameter optimization allows the solvent to maintain high-temperature stability for discharge while providing adequate solubility to prevent precipitation and ensure film flatness during vacuum drying.
Solution Approach 2:
The patent uses composite ink compositions containing multiple components: the functional material (Formula 1), the specific glycol ether-based solvent, and a p-type doping material. This composite formulation synergistically combines the high boiling point solvent's discharge stability with the functional material's film-forming properties and the doping material's solubility enhancement, resolving the contradiction between discharge reliability and film quality.
2Reliability
If a solvent with a high boiling point is used to prevent nozzle clogging, then discharge stability is improved, but film surface smoothness deteriorates due to precipitation during quick drying
Solution Approach 1:
The patent optimizes the solvent's chemical parameters by selecting glycol ether-based solvents with specific molecular structures that balance high boiling point (for discharge stability) and adequate solubility power (for preventing precipitation). The selected solvents have boiling points high enough to prevent nozzle clogging but with molecular characteristics that maintain material solubility during the vacuum drying process, ensuring smooth film surfaces.
Solution Approach 2:
The p-type doping material acts as an intermediary substance that enhances the compatibility between the functional material and the high-boiling-point solvent. It improves solubility and prevents precipitation during the quick vacuum drying process, thereby maintaining surface smoothness while allowing the use of high-boiling-point solvents for discharge stability.
3Reliability
If conventional solvents are used in the inkjet process, then discharge stability is poor, but using high boiling point solvents causes precipitation and surface roughness
Solution Approach 1:
The patent fundamentally changes the solvent selection parameters from conventional solvents to specifically selected glycol ether-based solvents with optimized boiling points and solubility characteristics. This parameter change enables the solvent to simultaneously provide discharge stability (high boiling point) and film image quality (adequate solubility, no precipitation) during the inkjet printing and vacuum drying process.
Solution Approach 2:
The patent develops a composite ink formulation consisting of the functional material (Formula 1), the optimized glycol ether-based solvent, and p-type doping material. This composite system synergistically resolves the contradiction by combining the high boiling point solvent's discharge stability with the doping material's solubility enhancement, achieving both reliable discharge and high-quality film images without precipitation or surface roughness.
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 composition achieves smooth and flat film surfaces, maintains discharge stability, and prevents nozzle clogging, thereby enhancing the efficiency and quality of the organic light emitting device layers.
Implementation Method 1
a compound represented by the following Chemical Formula 1, which includes a functional group that can be crosslinked by heat or light
Implementation Method 2
a glycol ether-based solvent with a high boiling point to ensure stable film formation and prevent nozzle clogging
Data Source
AI summary
The present invention relates to an ink composition for an organic light emitting device that can be applied to an inkjet process. When the inkjet process is applied using this, it is possible to form a film having smooth and flat surfaces when dried after forming an ink film.