Organic EL Capping Layer Benzazole Ring Light Extraction
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Solution Overview
Problem
Conventional organic electroluminescent elements with capping layers face issues such as decreased color purity and light extraction efficiency due to unabsorbed sunlight in the 400 nm to 410 nm wavelength range, and existing materials like ZnSe and Alq3 have limitations in stability and refractive index, leading to alignment accuracy problems and reduced efficiency.
Innovation Solution
An organic electroluminescent element with a capping layer composed of an amine compound having a benzazole ring structure, specifically designed to absorb light in the 400 nm to 410 nm range, providing a high refractive index and extinction coefficient, enhancing light extraction efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a capping layer with high refractive index is used to improve light extraction efficiency, then light extraction efficiency is improved, but color purity decreases due to unabsorbed sunlight in the 400 nm to 410 nm range
Solution Approach 1:
The patent converts the harmful effect of sunlight in the 400-410 nm range into a beneficial feature by using this specific wavelength range to excite the benzazole ring structure of the capping layer material. This absorption band, which would normally be considered harmful, is instead utilized to achieve both high light extraction efficiency and maintained color purity through the specific optical properties of the benzazole-containing compound.
Solution Approach 2:
The patent changes the optical parameters of the capping layer by selecting a material with a specific absorption spectrum characterized by a benzazole ring structure. This material has a high refractive index for improved light extraction while simultaneously having an extinction coefficient that absorbs unwanted sunlight wavelengths, thus changing the optical parameters to resolve the contradiction between light extraction efficiency and color purity.
2Ease of manufacture
If conventional materials like ZnSe or Alq3 are used for the capping layer, then manufacturing is easier, but alignment accuracy decreases due to distortion by heat
Solution Approach 1:
The patent changes the thermal and optical parameters of the capping layer material by selecting an organic compound containing a benzazole ring structure. This material maintains structural stability at deposition temperatures, preventing the distortion that occurs with inorganic materials like ZnSe, thereby maintaining alignment accuracy while remaining compatible with conventional deposition processes.
3Object-affected harmful factors
If the capping layer absorbs light in the 400 nm to 410 nm range, then color purity is improved, but light extraction efficiency may be reduced
Solution Approach 1:
The patent optimizes the optical parameters by selecting a material with a specific absorption spectrum. The benzazole ring structure provides an extinction coefficient that selectively absorbs sunlight in the 400-410 nm range while maintaining high refractive index properties for light extraction. This parameter optimization allows simultaneous achievement of color purity improvement and light extraction efficiency.
Solution Approach 2:
The patent uses a composite approach by incorporating the benzazole ring structure into an organic compound that also contains aromatic hydrocarbon groups. This composite molecular structure combines the light-absorbing property of the benzazole ring with the high refractive index and optical properties needed for efficient light extraction, resolving the contradiction between color purity and light extraction 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
The proposed solution results in an organic electroluminescent element with improved luminance, power efficiency, and extended life, maintaining color purity and optimizing light extraction across various wavelengths without affecting the internal materials.
Implementation Method 1
designed to absorb light in the 400 nm to 410 nm range
Implementation Method 2
when light emitted in a luminous layer enters another film at a given or greater angle, the light is totally reflected at an interface between the luminous layer and the other film
Data Source
AI summary
The present disclosure is related to an organic EL element including a capping layer that contains a compound represented by formula (A-1). In the formula, A and X are monovalent groups represented by formula (B-1) having 1 binding site among R1 to R6. Z represents a monovalent group represented by formula (B-1) having 1 binding site among R1 to R6, an aromatic hydrocarbon group, an aromatic heterocyclic group or a fused polycyclic aromatic group. Ar is a single bond or a divalent group of an aromatic hydrocarbon group, an aromatic heterocyclic group, or a fused polycyclic aromatic group. R1 to R6 are each defined in the specification, and Q represents a nitrogen atom, an oxygen atom, or a sulfur atom.