Solid Material for White OLED Evaporation
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Solution Overview
Problem
Current methods for producing white light emitting layers in organic electroluminescent devices require complex co-evaporation processes, are prone to variations in device performance due to differences in sublimation temperatures of materials, and are affected by water and oxygen adsorption, especially when using phosphorescent materials.
Innovation Solution
A light emitting layer-forming solid material comprising a host material and a phosphorescent light-emitting material, with a thermally conductive material, that allows for a single-layer structure formation by adjusting the evaporation cell temperature, reducing the need for co-evaporation and minimizing water and oxygen adsorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If co-evaporation method is used to form white light emitting layer, then multiple light emitting materials can be deposited, but the process becomes complex and device performance varies due to different sublimation temperatures
Solution Approach 1:
The patent combines multiple light emitting materials (host material and phosphorescent dopant) into a single pre-mixed solid material composition. This allows both materials to be deposited simultaneously from one evaporation source, eliminating the need for complex co-evaporation systems with multiple sources while maintaining the ability to form white light emitting layers.
Solution Approach 2:
The host material and phosphorescent dopant are pre-mixed in specific ratios before evaporation. This preliminary mixing ensures consistent composition in the deposited layer, avoiding the performance variations that occur when materials with different sublimation temperatures are deposited separately through co-evaporation.
2Illumination intensity
If phosphorescent light-emitting materials are used in powder form for co-evaporation, then light emission can be achieved, but water or oxygen adsorption on powder surfaces causes unstable device characteristics
Solution Approach 1:
The patent creates a composite solid material where the phosphorescent dopant is intimately mixed with the host material at the molecular level. This composite structure protects the phosphorescent material from water and oxygen adsorption that plagues powder forms, while maintaining efficient light emission through the host-guest interaction mechanism.
Solution Approach 2:
The evaporation process is conducted in a high vacuum environment (10^-5 to 10^-7 Pa), creating an inert atmosphere that prevents water and oxygen from adsorbing onto the phosphorescent material surfaces during deposition, thereby ensuring stable device characteristics.
3Manufacturing precision
If separate evaporation cells are used for different light emitting layers, then each layer can be optimized, but the production process becomes time-consuming
Solution Approach 1:
The patent merges the deposition of host material and phosphorescent dopant into a single evaporation step using a unified solid material composition. This eliminates the need for sequential deposition in separate cells, dramatically reducing production time while maintaining precise composition control through the pre-established mixing ratios.
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 stabilizes device characteristics, improves emission efficiency, and extends service life by controlling the composition of the evaporation film and reducing static electrical charges, while simplifying the production process.
Implementation Method 1
the heating temperature for the evaporation source (evaporation cell temperature) is changed while using only one type of light emitting layer-forming solid material, thereby controlling the composition of the resultant evaporation film
Implementation Method 2
A light emitting layer-forming solid material comprising a host material and a phosphorescent light-emitting material, with a thermally conductive material
Data Source
AI summary
A light emitting layer-forming solid material including at least one host material and at least one light-emitting material, wherein the light emitting layer-forming solid material is used for forming a white light emitting layer having a single layer structure by an evaporation method.