Organic Light-Emitting Element Optical Distance Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The 'white+CF system' for organic electroluminescent displays faces issues with lowered luminance and a tradeoff between emission efficiency and viewing angle characteristics due to the color filter, particularly in tandem-type elements where higher interference order degrades luminous intensity distribution.
Innovation Solution
An organic light-emitting element with a specific optical distance configuration between emission layers and a reflective electrode, along with a first organic compound layer with a refractive index of 1.70 or less, to enhance emission efficiency and viewing angle characteristics while reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a tandem element structure with multiple emission layers is used to improve emission efficiency through optical interference, then power consumption is reduced, but viewing angle characteristics are degraded due to higher order interference
Solution Approach 1:
The patent applies parameter changes by precisely controlling the optical distance between the emission layer and reflective electrode to satisfy the λ/4 interference condition, and by selecting materials with appropriate refractive indices (1.70 or less) to optimize both emission efficiency and viewing angle characteristics simultaneously
Solution Approach 2:
The patent applies local quality by creating specific optical conditions in different regions of the device - the optical distance and refractive index are optimized locally at the emission layer interface to enhance front emission while maintaining wide-angle viewing characteristics through controlled interference patterns
2Use of energy by moving object
If the optical distance between emission layer and reflective electrode is increased to enhance interference intensity for better emission efficiency, then power consumption decreases, but luminous intensity distribution uniformity across viewing angles deteriorates
Solution Approach 1:
The patent resolves this contradiction by changing the optical distance parameter to satisfy the λ/4 condition and controlling the refractive index to 1.70 or less, which optimizes the interference pattern to maintain uniform luminous intensity distribution across different viewing angles while achieving high emission efficiency
3Manufacturing precision
If a color filter is used in the white+CF system to achieve higher definition display, then pixel size and inter-pixel pitch are reduced, but luminance is lowered
Solution Approach 1:
The patent applies parameter changes by optimizing the optical distance and refractive index to enhance emission efficiency, which compensates for the luminance loss caused by the color filter, thereby maintaining both high definition and adequate luminance performance
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 solution improves both power consumption and viewing angle characteristics by optimizing the optical distances and refractive indices in the organic light-emitting element, achieving efficient white light emission with reduced color difference and emission intensity variation across angles.
Implementation Method 1
a reflective electrode, and a light extraction electrode... when light of a certain wavelength is incident on an interface between media having different refractive indices, a part of the light is reflected
Implementation Method 2
a first organic compound layer formed between the light extraction electrode and the first emission layer, and a refractive index of the first organic compound layer at the wavelength λ1 is 1.70 or less
Implementation Method 3
Light-emitting molecules have the property of emitting intense light toward space in which 'enhancing interference' of light occurs... optical interference to control an emission pattern
Implementation Method 4
An organic light-emitting element, which is self-emissive with a low drive voltage of several volts... an organic light-emitting element generally has a structure in which a reflective electrode having a metal reflecting layer, an emission layer, and a light extraction electrode are stacked
Data Source
AI summary
Provided is an organic light-emitting element for emitting white light in which an optical distance L1 between a first emission layer (52) and a reflective electrode (80) satisfies Expression (a), and an optical distance L2 between a second emission layer (72) and the reflective electrode (80) satisfies Expression (b):(λ1/8)×(3−(2φ1/π))<L1<(λ1/8)×(5−(2φ1/π)) (a); and(λ2/8)×(−(2φ2/π)−1)<L2<(λ2/8)×(−(2φ2/π)+1) (b), andin which a refractive index of a first charge transport layer (51) formed between a light extraction electrode (4) and the first emission layer (52) at the wavelength λ1 is 1.70 or less.