Organic EL Light-Emitting Layer Surface Uniformity
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Solution Overview
Problem
Current methods for producing organic electroluminescence devices fail to achieve sufficient surface uniformity in the light-emitting layer, which affects the device's performance and efficiency.
Innovation Solution
A method involving the application of a coating liquid containing a light-emitting material and a host material dissolved in a solvent, followed by heating above the melting temperature of the host material and the boiling point of the solvent, to form a light-emitting layer with a specific contact angle difference and surface roughness, ensuring uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional production methods (heating from rear surface or drying at glass transition temperature) are used, then the light-emitting layer can be formed, but the surface uniformity is insufficient
Solution Approach 1:
The invention changes the heating temperature parameter from conventional methods (heating from rear surface at -30°C to +30°C of glass transition temperature) to a new parameter range (heating at a temperature equal to or higher than the boiling point of the organic solvent). This temperature parameter change enables the organic solvent to evaporate completely, forming a uniform light-emitting layer surface without requiring complex rear surface heating apparatus.
Solution Approach 2:
The invention replaces the mechanical heating method (heating from rear surface) with a thermal evaporation mechanism. By heating the light-emitting layer at or above the boiling point of the organic solvent, the solvent evaporates and the host material forms a uniform film through self-leveling, eliminating the need for complex rear surface heating mechanical systems.
2Manufacturing precision
If heating temperature is increased to improve surface uniformity, then surface uniformity improves, but risk of decomposing organic compounds increases
Solution Approach 1:
The invention performs preliminary action by selecting an organic solvent with a boiling point lower than the decomposition temperature of the organic compounds (host material and light-emitting material). This preliminary selection ensures that when heating is applied, the solvent evaporates at a safe temperature that prevents decomposition of the organic compounds, while still achieving uniform surface formation.
Solution Approach 2:
The invention changes the temperature parameter to a specific range: equal to or higher than the boiling point of the organic solvent but lower than the decomposition temperature of the organic compounds. This parameter optimization enables complete solvent evaporation for uniform surface formation while maintaining the integrity of the organic materials.
3Manufacturing precision
If heating is performed to evaporate solvent and form uniform layer, then surface uniformity improves, but production time increases
Solution Approach 1:
The invention changes the heating temperature parameter to a high value (equal to or higher than the boiling point of the organic solvent). This high-temperature heating enables rapid solvent evaporation and quick formation of a uniform light-emitting layer surface, significantly reducing the required heating time compared to conventional low-temperature methods, thus improving production efficiency.
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 method significantly improves the surface uniformity of the light-emitting layer, leading to enhanced light emission efficiency and durability of the organic electroluminescence devices.
Implementation Method 1
heating the coating liquid applied to the adjacent layer at a temperature higher than a melting temperature of the host material and higher than a boiling point of the solvent
Implementation Method 2
heating the coating liquid applied to the adjacent layer at a temperature higher than a melting temperature of the host material
Implementation Method 3
Organic electroluminescence devices have advantageous features such as self emission and high-speed response
Data Source
Figure 1
AI summary
Provided is a method for producing an organic electroluminescence device which contains an anode, a cathode and an organic layer between the anode and the cathode where the organic layer contains a light-emitting layer and an adjacent layer adjacent to the light-emitting layer, the method including: applying to the adjacent layer a coating liquid prepared by dissolving or dispersing a light-emitting material and a host material in a solvent, and heating the coating liquid applied to the adjacent layer at a temperature higher than a melting temperature of the host material and higher than a boiling point of the solvent, to thereby form the light-emitting layer, wherein a difference as an absolute value between contact angle A (°) of the light-emitting layer with respect to pure water and contact angle B (°) of the adjacent layer with respect to pure water is 13 (°) or smaller.