Organic Light-Emitting Element With Delayed Blue Fluorescence
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Solution Overview
Problem
Organic light-emitting devices using phosphorescent materials face efficiency reduction due to triplet-triplet annihilation and color concentration issues, especially with high-energy blue phosphorescent materials having low stability and high costs, making it difficult to increase white emission intensity.
Innovation Solution
An organic light-emitting device configuration with a delayed blue fluorescent material, a green fluorescent material, and a red fluorescent material, separated by a spacer layer, which enhances energy transfer and emission efficiency by preventing direct carrier recombination in the blue material, allowing for well-balanced white light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescent materials are used to achieve high emission efficiency, then emission efficiency is improved, but triplet-triplet annihilation occurs at high current density causing efficiency to drop
Solution Approach 1:
The patent divides the light-emitting layer into multiple separate layers, each containing different phosphorescent materials (blue, green, red) doped in the same host material. This segmentation prevents direct interaction between different phosphorescent materials, thereby avoiding triplet-triplet annihilation while maintaining high emission efficiency across all color regions even at high current densities.
Solution Approach 2:
The patent uses a common host material as an intermediary medium to host multiple phosphorescent materials. The host material facilitates energy transfer to each phosphorescent dopant independently, preventing direct energy interaction between different phosphorescent materials that would cause triplet-triplet annihilation, while still enabling efficient white light emission.
2Illumination intensity
If blue phosphorescent material is used for high-energy emission, then white light emission is achieved, but stability is low and cost is high
Solution Approach 1:
The patent changes the chemical composition parameters by selecting specific phosphorescent materials with appropriate lifetime characteristics. By using blue phosphorescent materials with longer lifetimes and optimizing doping concentrations in the host material, the patent achieves stable blue emission while maintaining overall device stability and reducing reliance on expensive rare earth elements.
3Stability of the object's composition
If phosphorescent materials are mixed in one layer to achieve balanced emission, then color balance is improved, but precise density control is needed
Solution Approach 1:
The patent segments the mixed phosphorescent material system into separate doped layers within a unified host material structure. Each phosphorescent material (blue, green, red) is doped at optimized concentrations in separate regions, eliminating the need for precise mixed-density control while achieving well-balanced white light emission through the combined output of all layers.
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 device achieves high-efficiency white light emission with stable color purity and increased intensity, even at higher current densities, without significant reduction in whiteness, and maintains performance over long-term use.
Implementation Method 1
a layer containing a delayed blue fluorescent material
Implementation Method 2
enhances energy transfer and emission efficiency by preventing direct carrier recombination in the blue material
Implementation Method 3
a layer containing separately or together a green fluorescent material and a red fluorescent material
Data Source
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AI summary
An organic light-emitting device having a layer 10 containing a delayed blue fluorescent material, a layer 11 containing separately or together a green fluorescent material and a red fluorescent material, and a spacer layer 12 arranged between the layer 10 and the layer 11 can efficiently emit white color.