White OLED Emission Layer Segmentation for Luminance and Lifespan
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a tradeoff between color saturation, luminance, and lifespan in OLED devices, particularly in RGBW type OLEDs, where increased current density to compensate for reduced luminance leads to shortened lifespan and undesirable color shifts, and correcting color coordinates requires complex algorithms that increase power consumption.
Innovation Solution
A white OLED element is designed with a multi-layered emission layer structure featuring a blue electroluminescent layer and a complementary layer that emit blue and complementary light respectively, allowing for improved luminance and color accuracy without increasing driving voltage, and using color filters to generate red and green light without filtering blue light at the blue pixel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If white light from OLED element passes through color filter elements to generate red and green light, then color saturation is improved, but luminance is reduced
Solution Approach 1:
The invention segments the light generation process by using separate emission layers for blue light and white light. The blue emission layer generates blue light that passes through the blue color filter, while the white emission layer generates white light that passes through red and green color filters. This segmentation allows each color channel to be optimized independently, maintaining high luminance in the blue channel while achieving good color saturation in red and green channels.
Solution Approach 2:
The invention applies local quality by having different emission characteristics in different spatial regions. The blue emission layer is positioned to provide blue light specifically for the blue color filter region, while the white emission layer provides white light for the red and green color filter regions. This local optimization ensures that each pixel region receives the appropriate light characteristics for its function.
2Productivity
If higher current density is provided to compensate for reduced luminance, then luminance is improved, but lifespan is shortened
Solution Approach 1:
The invention segments the current distribution by directing higher current density specifically to the white emission layer while maintaining lower current density in the blue emission layer. This segmented current allocation allows the white emission layer (which requires higher luminance due to color filter losses) to receive more current, while the blue emission layer maintains lower current to preserve its lifespan.
Solution Approach 2:
The invention changes the current density parameter differently for different emission layers. By adjusting the current density distribution to be higher for the white emission layer and lower for the blue emission layer, the system compensates for luminance losses in red and green pixels without over-driving the blue emission layer, thus extending overall device lifespan.
3Measurement precision
If driving voltage is increased to correct color coordinate shift, then color accuracy is improved, but power consumption increases
Solution Approach 1:
The invention performs preliminary action by pre-correcting color coordinate issues through the structural design of the emission layers and color filters. By optimizing the emission spectra of the blue and white emission layers and matching them with appropriate color filters, the system achieves accurate color coordinates without requiring additional corrective voltage adjustments during operation.
Solution Approach 2:
The invention extracts the color correction function from the electrical control domain (voltage adjustment) and transfers it to the optical design domain (emission layer and filter design). By carefully selecting the emission characteristics of the organic compounds and the transmission characteristics of the color filters, the system achieves color accuracy through optical means rather than electrical compensation.
4Productivity
If blue light luminance is maintained without color filter, then emission efficiency is improved, but color saturation may be reduced
Solution Approach 1:
The invention applies local quality by providing different optical paths for different color channels. In the blue color filter region, the blue emission layer provides blue light that passes through the blue color filter, achieving both high emission efficiency and good color saturation. The blue color filter is specifically designed to transmit blue light while blocking other wavelengths, ensuring color purity without excessive luminance loss.
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 configuration enhances emission efficiency and lifespan by maintaining blue light luminance and color accuracy, reducing power consumption, and providing flexibility in pixel layout designs.
Implementation Method 1
a blue electroluminescent layer configured to emit substantially blue light
Implementation Method 2
a complementary emission layer configured to emit light that complements the blue light such that the blue light from the blue electroluminescent layer and the light emitted from the complementary emission layer collectively form substantially white light
Implementation Method 3
color filters to generate red and green light without filtering blue light at the blue pixel
Data Source
Figure 1a~1c
Figure 2a~2c
Figure 2d~2e
AI summary
A white organic light emitting element, a white organic light emitting display device, and a method of manufacturing the white organic light emitting element are provided. The organic light emitting element includes a multi-layered emission layer structure. The multi-layered emission layer structure includes a first electroluminescent layer and a second electroluminescent layer that are arranged to overlap at first area of the white organic light emitting element. The lights from the first and second electroluminescent layers collectively form white light. Among the first and second electroluminescent layers, one of the EL layers is extended out to the second area of the white organic light emitting element. A plurality of color filter elements are used to filter the white light to generate colored lights at the corresponding sub pixel regions.