OLED Microcavity Emission Layer Segmentation
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Solution Overview
Problem
Organic light emitting devices face limitations in emission efficiency, service life, and power consumption, particularly with blue pixels having shorter service life and increased power consumption when trying to enhance luminance and resolution.
Innovation Solution
The use of a micro cavity structure with different materials for the first and second emission layers in each pixel, such as a combination of fluorescent and phosphor materials, to optimize light emission and extend service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If emission efficiency is enhanced by changing to phosphor material, then luminance is improved, but service life is reduced and power consumption increases
Solution Approach 1:
The emission layer is divided into multiple sub-layers (first emission layer, second emission layer, third emission layer) with different materials and functions. Each sub-layer contributes differently to light emission, allowing the device to achieve high luminance through cumulative effect while individual layers can be optimized for longevity, thus resolving the contradiction between luminance enhancement and service life reduction
Solution Approach 2:
Different regions of the emission layer have different material compositions and optical properties. The first emission layer uses one material system while the second and third layers use different materials, creating local quality variations that allow simultaneous optimization of luminance output and operational stability in different parts of the device
2Illumination intensity
If emission efficiency is enhanced by changing to phosphor material, then luminance is improved, but power consumption increases
Solution Approach 1:
The emission layer is segmented into multiple sub-layers with different materials and emission characteristics. This segmentation allows the device to achieve high luminance through the combined effect of multiple layers rather than relying on a single high-power phosphor layer, thereby distributing the energy demand and reducing overall power consumption while maintaining high luminance output
3Reliability
If blue pixel service life is extended, then overall device reliability is improved, but emission efficiency may be compromised
Solution Approach 1:
The blue pixel emission is achieved through local quality differentiation where the first emission layer uses materials optimized for longevity while the second and third layers use materials optimized for emission efficiency. This local differentiation allows the blue pixel to achieve both extended service life and maintained emission efficiency through the combined output of the layered structure
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 enhances emission efficiency, extends service life, and reduces power consumption, particularly for blue pixels, while maintaining high luminance and color accuracy.
Implementation Method 1
The anode electrode 10 is formed as a reflective electrode, and the cathode electrode 70 is formed as a semi-transmissive electrode, thereby forming a micro cavity structure. An optical cavity is formed between the cathode electrode 70 and the anode electrode 10. The cathode electrode 70 transmits some (for example, 60%) of light emitted from the organic emission layer, and the remaining light (for example, 40%) which is not transmitted is reflected to cause constructive interference suitable for each wavelength, thereby enhancing emission efficiency.
Implementation Method 2
When an electron generated from the cathode electrode 70 and a positive hole generated from the anode electrode 10 are injected into the EMLs 52, 54 and 56, the injected electron and positive hole are combined to generate an exciton. The generated exciton is shifted from an excited state to a ground state to emit red light, green light, and blue light from the red EML 52, the green EML 54, and the blue EML 56.
Data Source
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AI summary
Disclosed is an organic light emitting device. The organic light emitting device includes a red pixel configured to include a first red emission layer and a second red emission layer which emit red light, a green pixel configured to include a first green emission layer and a second green emission layer which emit green light, a blue pixel configured to include a first blue emission layer and a second blue emission layer which emit blue light, a first electrode formed as a reflective electrode, and configured to supply an electric charge having a first polarity to the red pixel, the green pixel, and the blue pixel, and a second electrode formed as a transmissive or semi-transmissive electrode, and configured to supply an electric charge having a second polarity to the red pixel, the green pixel, and the blue pixel.