Mixed-Solvent Emission Layer Ink for Efficient LED Printing
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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
The use of a mixed solvent with specific vapor pressure, boiling point, and Hansen parameters, along with a controlled evaporation rate, is employed to form the emission layer through inkjet printing, enhancing the orthogonality and efficiency of the layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solvents are used in the emission layer formation, then the manufacturing process is simple, but the luminous efficiency and lifespan are insufficient
Solution Approach 1:
The patent changes the physical and chemical parameters of the solvent system by selecting specific solvents with defined vapor pressures (1×10^-4 to 10 mmHg) and boiling points (80-200°C), and controlling their ratios (first solvent 5-50 wt%, second solvent 50-95 wt%). This parameter optimization enables proper solvent evaporation during inkjet printing, ensuring high luminous efficiency and extended LED lifespan without overly complicating the manufacturing process
Solution Approach 2:
The patent employs a composite solvent system consisting of multiple solvents with complementary properties: a first solvent (e.g., toluene, chloroform) providing good dissolving power and a second solvent (e.g., cyclohexane, diethyl ether) with lower boiling point for controlled evaporation. This composite approach creates synergistic effects that improve emission layer quality and device performance while maintaining manufacturing feasibility
2Productivity
If high boiling point solvents are used, then the emission layer stability is improved, but the drying process efficiency decreases
Solution Approach 1:
The patent segments the solvent evaporation process into distinct stages by using a multi-component solvent system with different volatility characteristics. The second solvent (lower boiling point) evaporates first during the initial drying phase, followed by the first solvent (higher boiling point) in subsequent phases. This segmented evaporation ensures efficient drying while maintaining emission layer stability through controlled solvent removal
Solution Approach 2:
The patent optimizes the boiling point parameter of the solvent mixture to fall within 80-200°C, with the second solvent having a boiling point 20-80°C lower than the first solvent. This parameter control enables the drying process to complete within 10-60 seconds at 100-200°C, achieving both high productivity and composition stability
3Productivity
If the solvent evaporation rate is increased, then the manufacturing speed is improved, but the material compatibility and layer orthogonality deteriorate
Solution Approach 1:
The patent carefully balances the evaporation rate parameter by selecting solvents with vapor pressures in the range of 1×10^-4 to 10 mmHg and controlling the drying temperature at 100-200°C. This parameter optimization achieves complete solvent evaporation within 10-60 seconds while preventing premature drying that would compromise material compatibility and layer orthogonality, thus maintaining both high manufacturing speed and precision
4Manufacturing precision
If low vapor pressure solvents are used, then the emission layer uniformity is improved, but the drying time increases
Solution Approach 1:
The patent segments the solvent system into two components with different vapor pressures: the first solvent (5-50 wt%) with lower vapor pressure for uniformity and the second solvent (50-95 wt%) with higher vapor pressure for faster evaporation. This segmentation enables the drying process to complete quickly while maintaining emission layer uniformity through the coordinated action of both solvents
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 results in increased luminous efficiency and extended lifespan of the LEDs by ensuring proper solvent evaporation and material compatibility, thereby improving the overall performance of the diodes.
Implementation Method 1
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.