Mixed-Solvent Ink Composition for Uniform LED Emission Layers
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Solution Overview
Problem
Existing light emitting diodes (LEDs) face challenges in achieving high luminous efficiency and lifespan due to inefficiencies in the manufacturing process, particularly in the formation of the emission layer.
Innovation Solution
Incorporating a mixed solvent with specific vapor pressure, boiling point, and Hansen parameters in the ink composition for the emission layer, along with a controlled evaporation rate and temperature, enhances the efficiency and lifespan of the LED by improving the formation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solvents are used in the ink composition for emission layer formation, then the manufacturing process is simple, but the luminous efficiency and lifespan of the LED are reduced
Solution Approach 1:
The patent applies parameter changes by carefully selecting solvents with specific vapor pressure ranges (1×10^-4 to 10 mmHg) and boiling point ranges (80°C to 270°C). This quantitative parameter optimization enables efficient solvent evaporation during emission layer formation, directly improving LED lifespan and luminous efficiency without overly complicating the manufacturing process
Solution Approach 2:
The patent uses composite solvent systems comprising multiple solvents with complementary properties. The mixed solvent composition (e.g., toluene and ethyl acetate in specific ratios) creates a synergistic effect that optimizes both evaporation characteristics and compatibility with light-emitting materials, resolving the contradiction between reliability improvement and process complexity
2Productivity
If high boiling point solvents are used, then the emission layer has good stability, but the drying process efficiency is reduced
Solution Approach 1:
The patent optimizes the boiling point parameter of solvents to fall within 80°C to 270°C, with preferred ranges of 100°C to 200°C. This parameter optimization ensures that solvents evaporate at controlled rates during the drying process, improving productivity while maintaining emission layer stability through appropriate thermal processing
Solution Approach 2:
The patent applies local quality by using solvents with different volatility characteristics in specific combinations. More volatile solvents (lower boiling point) evaporate first to prevent material aggregation, while less volatile solvents (higher boiling point) remain longer to ensure complete material dissolution and uniform distribution, achieving both fast drying and stable emission layers
3Reliability
If solvents with inappropriate vapor pressure are used, then the manufacturing process is simple, but the luminous efficiency is reduced
Solution Approach 1:
The patent specifies vapor pressure parameters for solvents (1×10^-4 to 10 mmHg at specific temperatures) to optimize the balance between solvent retention during material deposition and solvent removal during drying. This parameter control ensures proper emission layer formation for high luminous efficiency while maintaining manufacturability through standardized processing conditions
Solution Approach 2:
The patent uses specifically selected solvents as intermediaries that facilitate the transition from liquid ink composition to solid emission layer. The intermediary solvents temporarily hold the light-emitting materials in solution during deposition, then evaporate controllably to leave behind the functional emission layer, achieving high luminous efficiency without complex manufacturing steps
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 use of a mixed solvent with defined properties in the ink composition results in improved luminous efficiency and extended lifespan of the LEDs by ensuring proper layer formation and minimizing material mixing, thereby optimizing the manufacturing process.
Implementation Method 1
The ink composition may include a mixed solvent including a first solvent and a second solvent, and a light emitting material. The first solvent and the second solvent each may have a vapor pressure of about 1×10−4 or greater and a boiling point of about 270° C. or less.
Data Source
AI summary
An ink composition including a mixed solvent including a first solvent and a second solvent, and a light emitting material, wherein the first solvent and the second solvent each have a vapor pressure of about 1×10−4 or greater and a boiling point of about 270° C. or less. The ink composition according to an embodiment may be applied to forming an emission layer of a light emitting diode to provide a light emitting diode having increased efficiency.