Organic Light-Emitting Element Cover Layer Boron Complex
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Solution Overview
Problem
Existing organic light-emitting elements face challenges in achieving both high luminous efficiency and high color purity, particularly for blue light-emitting elements, due to limitations in the refractive index and stability of materials used in the cover layers.
Innovation Solution
A laminate cover layer structure comprising a high refractive index layer and a low refractive index layer, where the low refractive index layer is formed from a boron complex compound, is used to enhance light extraction efficiency and color purity. The boron complex compound is specifically designed to have a low refractive index and excellent thin film stability, improving the performance of the organic light-emitting element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional organic cover layer materials (amine derivatives, quinolinol complexes) are used to increase refractive index for light extraction, then light extraction efficiency is improved, but color purity deteriorates due to absorption in blue wavelength region
Solution Approach 1:
The patent changes the refractive index parameter of the cover layer material by selecting a boron complex compound with inherently low refractive index (1.6-1.7), eliminating the need for high refractive index materials that cause blue light absorption. This parameter change resolves the contradiction by achieving adequate light extraction without compromising color purity.
Solution Approach 2:
The patent uses a composite cover layer structure comprising multiple layers with different refractive indices (first cover layer with n=1.6-1.7, second cover layer with n=1.8-2.0). This composite structure optimizes both light extraction efficiency and color purity by distributing optical functions across layers with complementary properties.
2Reliability
If thin film stability is improved by using conventional materials, then reliability is enhanced, but light extraction efficiency and color purity cannot be simultaneously optimized
Solution Approach 1:
The patent identifies and utilizes specific parameter ranges for the boron complex compound (refractive index 1.6-1.7, triplet energy 2.1-3.0 eV) that simultaneously satisfy both stability requirements and optical performance requirements, achieving a win-win solution rather than a trade-off.
Solution Approach 2:
The patent employs a boron complex compound that forms a stable thin film structure, replacing materials that require complex multi-layer structures to achieve comparable stability. This simplifies the device structure while maintaining or improving performance.
3Ease of manufacture
If a single-layer cover structure is used to simplify manufacturing, then ease of manufacture is improved, but inability to simultaneously achieve high light extraction efficiency and color purity
Solution Approach 1:
The patent changes the material parameter to a boron complex compound that inherently provides both low refractive index and high stability, allowing a single-layer structure to achieve performance previously requiring complex multi-layer structures, thus simplifying manufacturing.
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 use of a boron complex compound in the low refractive index layer significantly improves light extraction efficiency and color purity, achieving high luminous efficiency and stability, which is not attainable with previous materials.
Implementation Method 1
a low refractive index layer formed from a boron complex compound... significantly improves light extraction efficiency
Implementation Method 2
adjust an optical interference distance, suppress external light reflection and extinction caused by surface plasma energy movement
Implementation Method 3
light is generated when holes and electrons injected from an electrode return to a ground state via an excited state by recombination in a light-emitting layer
Data Source
AI summary
The present invention provides an organic light-emitting element, comprising a substrate, a first electrode, more than one organic layer film comprising a light-emitting layer, and a second electrode. The light-emitting element further comprises a cover layer. The cover layer is located on the second electrode, and comprises a high refractive layer and a low refractive layer. A material for the low refractive layer of the cover layer is a boron complex organic small molecular compound. The organic light-emitting element provided by the present invention can achieve high light-emitting efficiency and color reproducibility. The organic light-emitting element of the present invention can be used for an organic EL display, a backlight source of a liquid crystal display, illumination, a sign board, an identification lamp, etc.