OLED Micro-Cavity Design for Luminous Efficiency and Color Purity
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Solution Overview
Problem
Current organic light emitting display (OLED) devices face limitations in achieving high luminous efficiency and color purity, particularly in multi-color pixel configurations, due to inefficient energy transfer and resonance mechanisms within micro-cavities.
Innovation Solution
The implementation of a display apparatus with a micro-cavity structure that includes multiple organic light emitting material layers, where each pixel emits a different wavelength band, utilizing reflective layers with nanostructures and color filters to enhance resonance and energy transfer, allowing for improved luminous efficiency and color purity through optimized micro-cavity design and dopant configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple organic light emitting material layers are used in a single pixel, then color purity is improved, but device complexity increases
Solution Approach 1:
The pixel is segmented into multiple organic light emitting material layers, each emitting a specific wavelength band. The first pixel includes a first organic light emitting material layer emitting blue light (450-480nm), a second organic light emitting material layer emitting green light (500-550nm), and a third organic light emitting material layer emitting red light (600-650nm). This segmentation enables each layer to specialize in emitting a specific color, thereby improving overall color purity while maintaining manageable device complexity through systematic organization.
Solution Approach 2:
Different regions of the pixel are assigned different light emitting materials with specific properties optimized for their intended wavelength band. Each organic light emitting material layer is positioned at specific locations within the pixel structure, with the blue-emitting layer positioned to resonate with the first micro-cavity, the green-emitting layer with the second micro-cavity, and the red-emitting layer with the third micro-cavity. This local optimization of material properties and positions enhances color purity without uniformly increasing complexity across the entire device.
2Use of energy by moving object
If micro-cavity resonance is optimized for one wavelength band, then luminous efficiency for that band is improved, but luminous efficiency for other wavelength bands deteriorates
Solution Approach 1:
The pixel structure is designed with multiple micro-cavities (first, second, and third micro-cavities) that can simultaneously resonate with different wavelength bands. Each micro-cavity is configured with specific dimensions and reflective layer properties to resonate with its corresponding organic light emitting material layer's emission wavelength. This multi-functional design allows the single pixel to efficiently emit multiple colors (blue, green, and red) simultaneously, achieving high luminous efficiency across multiple wavelength bands rather than optimizing for just one.
Solution Approach 2:
The solution transitions from a single-wavelength optimization approach to a multi-wavelength approach by adding vertical layering and multiple micro-cavity structures. Instead of trying to optimize a single cavity for all wavelengths, the invention uses multiple cavities at different positions and orientations, each tuned to specific wavelength bands. This dimensional expansion of the resonance structure enables simultaneous optimization for multiple wavelength bands, resolving the trade-off between luminous efficiency and wavelength coverage.
3Use of energy by moving object
If energy transfer between dopants is enhanced, then luminous efficiency is improved, but color purity deteriorates due to unwanted wavelength emission
Solution Approach 1:
The invention extracts and removes the color filter layer from the pixel structure, replacing it with resonant micro-cavity structures that inherently emit only specific wavelength bands. Instead of using broad-spectrum light emission followed by filtering (which wastes energy and reduces efficiency), the system directly generates narrow-band light through resonant cavities. This extraction of the filtering function and replacement with resonant emission maintains high luminous efficiency while achieving color purity through the physics of resonance rather than through absorption and re-emission processes that would cause energy 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 approach significantly increases luminous efficiency by up to 362% for blue light and 355% for red light, while maintaining high color purity by reducing unwanted wavelength emission, as demonstrated in comparative examples.
Implementation Method 1
the reflective layer and the second electrode define a first micro-cavity in which the light of the first wavelength band resonates
Implementation Method 2
the second organic light emitting material layer of the first pixel and the third organic light emitting material layer of the first pixel may be disposed adjacent to or mixed with each other to enable energy transfer from the second light emitting dopant to the third light emitting dopant
Implementation Method 3
a first organic light emitting material layer which emits the light of the first wavelength band, a second organic light emitting material layer which emits the light of the second wavelength band, and a third organic light emitting material layer which emits the light of the third wavelength band
Implementation Method 4
a first color filter disposed on the second electrode of the first pixel to transmit the light of the first wavelength band
Implementation Method 5
a reflective layer; a first electrode disposed on the reflective layer of the first pixel
Data Source
AI summary
A display apparatus includes first to third pixels, and the first pixel includes a reflective layer; a first electrode; a light emitting layer; a second electrode; and a first color filter to transmit light of the first wavelength band. The reflective layer and the second electrode define a micro-cavity in which the light of the first wavelength band resonates. The light emitting layer includes a first organic light emitting material layer which emits the light of the first wavelength band, a second organic light emitting material layer which emits the light of the second wavelength band, and a third organic light emitting material layer which emits the light of the third wavelength band.