High-Refractive Capping Layer for OLED Light Extraction
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Solution Overview
Problem
Current light emitting elements for organic electroluminescence display devices face challenges in achieving low driving voltage, high luminous efficiency, and long lifespan, with existing capping layers not adequately addressing light extraction efficiency.
Innovation Solution
A light emitting element is developed with a high-refractive capping layer containing a fused compound represented by specific formulas, which includes a monomolecular refractive index of about 1.7 to 2.5 for light with a wavelength of 490 nm to 570 nm, and a density of 1.0 to 1.3 g/cm3, enhancing light extraction efficiency and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional capping layer is applied to protect base materials, then the structural protection function is achieved, but the light extraction efficiency remains insufficient
Solution Approach 1:
The patent changes the refractive index parameter of the capping layer material from conventional values to high refractive index values (greater than 1.7 at 550 nm wavelength), which fundamentally alters the optical properties to improve light extraction efficiency while maintaining protective functions
Solution Approach 2:
The patent employs composite material strategies by combining high refractive index materials with specific molecular structures (containing heteroatoms like S, Se, Te) to achieve both high refractive index and appropriate density, optimizing both optical performance and structural protection
2Loss of energy
If the refractive index of the capping layer is increased to improve light extraction efficiency, then the luminous efficiency improves, but the material selection and structural design become more complex
Solution Approach 1:
The patent systematically explores and optimizes molecular structures containing heteroatoms (S, Se, Te) to achieve target refractive index values, providing a clear material design pathway that reduces selection complexity while achieving high luminous efficiency
Solution Approach 2:
The patent introduces specific functional groups and heteroatom arrangements at molecular level to locally enhance refractive index properties, allowing targeted optimization of optical characteristics without requiring complete redesign of the entire material system
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 high-refractive capping layer significantly improves light extraction efficiency and extends the lifespan of light emitting elements, meeting the demands for low driving voltage and high luminous efficiency in organic electroluminescence display devices.
Implementation Method 1
High-refractive capping layers for increasing light extraction efficiency of light generated from an emission layer are under development and research
Implementation Method 2
High-refractive capping layers for increasing light extraction efficiency of light generated from an emission layer
Data Source
AI summary
A light emitting element may include: a first electrode; a second electrode facing the first electrode; at least one functional layer disposed between the first electrode and the second electrode; and a capping layer disposed on the second electrode and including a fused compound represented by Formula 1 below. The capping layer possesses high refractive characteristics.