Organic Light Emitting Element Function Layer Film Uniformity
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Solution Overview
Problem
The challenge in forming organic light emitting elements is achieving a flat function layer with minimal film thickness difference between the central and end portions, as existing wet systems often result in uneven film thickness, affecting light emission characteristics.
Innovation Solution
A solution containing a functional material and a solvent with a high-boiling-point solvent having a viscosity of 13 mPa·s to 25 mPa·s and surface tension of 33 mN/m to 37 mN/m is used, which reduces film thickness differences by controlling the solvent's properties during the drying process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a wet system is used to form the function layer by applying and drying a solution, then the manufacturing process is simple and cost-effective, but the film thickness becomes uneven with larger differences between end portions and central portion
Solution Approach 1:
The patent applies parameter changes by carefully selecting and controlling the viscosity (13-25 mPa·s) and surface tension (33-37 mN/m) of the high-boiling-point solvent to achieve uniform film thickness. By adjusting these physical parameters of the solvent, the drying process produces a flat function layer with minimal thickness variation between central and end portions, resolving the contradiction between simple manufacturing and precise film uniformity.
2Measurement precision
If the pixel size is reduced to 500 μm or less for high-definition images, then the display resolution is improved, but the function layer film thickness must be reduced to several tens to several hundreds of nanometers which is difficult to control
Solution Approach 1:
The patent uses parameter changes by optimizing the solvent's viscosity and surface tension within specific ranges to achieve precise control of ultra-thin film formation. This allows the function layer to be formed at the required thickness of several tens to several hundreds of nanometers with high uniformity, enabling high-definition pixel sizes of 500 μm or less while maintaining manufacturing feasibility.
3Illumination intensity
If the function layer film thickness is reduced to several tens to several hundreds of nanometers, then the light emission characteristics are improved, but the film becomes more sensitive to thickness variations and harder to form flat
Solution Approach 1:
The patent applies parameter changes by selecting a high-boiling-point solvent with specifically controlled viscosity (13-25 mPa·s) and surface tension (33-37 mN/m). These parameter adjustments ensure that even at ultra-thin film thicknesses of several tens to several hundreds of nanometers, the function layer forms with high flatness and uniformity, maintaining excellent light emission characteristics while achieving the required manufacturing precision.
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 ensures a more uniform film thickness, enhancing the light emission characteristics of the organic light emitting elements by maintaining the viscosity and surface tension within specific ranges, thereby improving the flatness and consistency of the function layer.
Implementation Method 1
a wet system in which a solution containing a functional material and a solvent is applied to an upper side of the electrode, and the applied solution is dried to form the function layer
Implementation Method 2
The high-boiling-point solvent has a viscosity of from 13 mPa·s to 25 mPa·s, inclusive, and a surface tension of from 33 mN/m to 37 mN/m, inclusive
Implementation Method 3
The high-boiling-point solvent has a viscosity of from 13 mPa·s to 25 mPa·s, inclusive, and a surface tension of from 33 mN/m to 37 mN/m, inclusive
Data Source
AI summary
A solution contains a functional material for constituting a function layer, and a solvent. The solvent contains a high-boiling-point solvent composed of one or more solvent components having a boiling point of not less than 200° C. The high-boiling-point solvent has a viscosity of from 13 mPa·s to 25 mPa·s, inclusive, and a surface tension of from 33 mN/m to 37 mN/m, inclusive.