Self-luminous element dual optical cavity structure
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Solution Overview
Problem
Existing light-emitting elements face challenges in achieving optimal light extraction efficiency, particularly for shorter wavelengths like blue light, due to insufficient film thickness of functional layers, leading to inefficient luminous performance and color shifts.
Innovation Solution
The implementation of a dual optical cavity structure within light-emitting elements, where the first cavity corresponds to a longer peak wavelength and the second cavity to a shorter peak wavelength, optimized by varying the refractive indices of the transmissive layers, allows for the extraction of light at a desired wavelength, enhancing luminous efficiency and extending the operating life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the film thickness of functional layers is increased to improve light extraction efficiency, then the light extraction efficiency improves, but the peak wavelength shifts to longer wavelengths due to optical cavity effects
Solution Approach 1:
The optical cavity is segmented into two distinct cavities: a first optical cavity between the first electrode and second electrode, and a second optical cavity between the first electrode and the interface between the first and second light-transmissive layers. Each cavity targets a different wavelength range, with the first cavity addressing longer wavelengths and the second cavity addressing shorter wavelengths, thereby resolving the wavelength shift problem while maintaining high light extraction efficiency
Solution Approach 2:
The invention changes the optical parameters by introducing two light-transmissive layers with different refractive indices (difference of 0.3 or greater). The first light-transmissive layer has a higher refractive index than the second light-transmissive layer, creating distinct optical pathways that enable independent optimization of different wavelength ranges without compromising overall performance
2Power
If the film thickness of functional layers is optimized for device performance, then the luminous efficiency improves, but the light extraction efficiency decreases due to insufficient thickness
Solution Approach 1:
The dual cavity structure segments the light extraction function into two wavelength-specific cavities. The first cavity optimizes extraction for longer wavelengths while the second cavity optimizes extraction for shorter wavelengths, allowing the functional layers to maintain their optimal thin film thickness for luminous efficiency while achieving high overall light extraction efficiency through the combined action of both cavities
3Ease of manufacture
If a single optical cavity structure is used to improve light extraction efficiency, then the manufacturing is simplified, but the color accuracy deteriorates due to wavelength shifts
Solution Approach 1:
Rather than using a single complex cavity structure, the invention segments the system into two simpler, well-defined cavities with clear interfaces. The first cavity is defined by the electrode assembly, and the second cavity is defined by the interface between the two light-transmissive layers. This segmentation achieves color accuracy through wavelength-specific optimization while maintaining manufacturing simplicity through the use of standard layering techniques
Solution Approach 2:
Different regions of the optical system are assigned different qualities: the first light-transmissive layer has a higher refractive index optimized for one wavelength range, while the second light-transmissive layer has a lower refractive index optimized for another wavelength range. This local differentiation of optical properties enables precise color control across the spectrum while maintaining overall structural simplicity
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
This approach effectively optimizes the film thickness of functional layers, improves light extraction efficiency, and reduces color shifts, thereby enhancing the luminous efficiency and extending the operating life of light-emitting elements.
Implementation Method 1
A first optical cavity structure is formed between a surface of the first electrode facing the light-emitting layer and a surface of the second electrode facing the light-emitting layer. The first optical cavity structure corresponds to a first wavelength as a peak wavelength
Implementation Method 2
A second optical cavity structure is formed between the surface of the first electrode facing the light-emitting layer and an interface between the first light-transmissive layer and the second light-transmissive layer. The second optical cavity structure corresponds to a second wavelength as a peak wavelength
Implementation Method 3
a first electrode that is light-reflective
Implementation Method 4
a second electrode that is light-transmissive and is disposed above the light-emitting layer; a first light-transmissive layer disposed on the second electrode; and a second light-transmissive layer disposed on the first light-transmissive layer
Data Source
AI summary
A light-emitting element includes: a light-reflective first electrode; a light-emitting layer above the first electrode; a light-transmissive second electrode above the light-emitting layer; a first light-transmissive layer on the second electrode; and a second light-transmissive layer on the first layer. First optical cavity structure is formed between surface of the first electrode facing the light-emitting layer and surface of the second electrode facing the light-emitting layer. The first optical cavity structure corresponds to, as peak wavelength, first wavelength longer than peak wavelength of light emitted from the light-emitting layer. Second optical cavity structure is formed between the surface of the first electrode facing the light-emitting layer and an interface between the first layer and the second layer. The second optical cavity structure corresponds to, as peak wavelength, second wavelength shorter than the first wavelength. The first and second layers differ in refractive index from each other by 0.3 or greater.