Hybrid MicroLED Pixel Structure for Adhesive-Free Color Conversion
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Solution Overview
Problem
The challenge of thermal management and down-conversion efficiency in microLED arrays is exacerbated by the generation of waste heat from ultraviolet light sources, which can affect device lifetime and performance due to the sensitivity of down-conversion materials to excess heat.
Innovation Solution
A method involving the formation of pixel isolation structures on a sacrificial substrate, allowing separate processing that avoids damage to the backplane, followed by attachment to the microLEDs, enabling self-aligned and self-cured color-conversion layers without an adhesive layer between the light sources and conversion layers, and allowing for pre-testing and replacement of defective pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pixel isolation structures are formed directly on the backplane with light sources, then processing integration is improved, but the backplane and light sources may be damaged during processing
Solution Approach 1:
The fabrication process is segmented into two independent stages: first forming pixel isolation structures on a sacrificial substrate, then transferring them to the backplane. This separation allows each component to be processed independently without mutual interference, preventing damage to the backplane while maintaining processing integration.
Solution Approach 2:
A sacrificial substrate is introduced as an intermediary carrier for the pixel isolation structures during fabrication. This mediator allows the isolation structures to be formed and processed without direct contact with the backplane, protecting the backplane from processing damage while enabling subsequent precise transfer and alignment.
2Ease of manufacture
If adhesive layers are used between substrates and pixel isolation structures, then assembly is simplified, but light scattering increases reducing emission quality
Solution Approach 1:
The adhesive layer between the pixel isolation structures and the backplane is completely removed through selective release from the sacrificial substrate. This extraction eliminates the light-scattering adhesive interface while maintaining structural assembly through alternative bonding methods applied only where necessary.
Solution Approach 2:
Adhesive bonding is applied locally only at specific interfaces where structural support is needed (such as between the transparent substrate and pixel isolation structures), while eliminating adhesive at the light-emitting interface between the backplane and pixel isolation structures to prevent light scattering.
3Manufacturing precision
If color-conversion layers are formed after substrate assembly, then alignment is improved, but defective pixels cannot be replaced
Solution Approach 1:
Pixel isolation structures are pre-formed on a sacrificial substrate before final assembly, creating a stable platform for subsequent color-conversion layer formation. This preliminary structuring enables precise alignment while maintaining modular architecture that allows defective pixels to be replaced after color-conversion layers are formed by accessing the backplane through the transparent substrate.
4Illumination intensity
If ultraviolet light sources are used for high brightness, then illumination intensity is improved, but thermal management becomes more difficult affecting device lifetime
Solution Approach 1:
The pixel isolation structures are transferred from the sacrificial substrate to the backplane without adhesive, extracting the light-scattering interface and improving light extraction efficiency. This enhances the utilization of ultraviolet light for color conversion while reducing thermal load from light scattering losses, improving thermal management alongside brightness 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
This approach enhances thermal management, improves light emission quality by reducing light scattering, and allows for efficient, reliable formation of pixel structures with the ability to test and replace defective pixels, thereby improving the overall performance and longevity of microLED arrays.
Implementation Method 1
The stimulus may include a laser, and the laser may be provided with a focal length that focuses at the first adhesive layer and that does not focus at second adhesive layer
Implementation Method 2
The stimulus may include a laser that emits light at a wavelength, and the wavelength may disrupt the first adhesive layer without disrupting the second adhesive layer
Implementation Method 3
The first adhesive layer may have a melting point that is lower than the second adhesive layer. The stimulus may include a temperature that causes the first adhesive layer to melt without causing the second adhesive layer to melt
Implementation Method 4
Flat panel displays are made possible by pixel structures that produce monochromatic ultraviolet light that is subsequently down-converted into visible light
Implementation Method 5
the pixel isolation structures may isolate the light sources from each other
Data Source
AI summary
A method of forming a micro light-emitting diode (microLED) array may include forming pixel isolation structures on a sacrificial substrate, and mounting the microLEDs on a separate backplane. The processes that forms the pixel isolation structures, and which may damage the backplane or microLEDs can be separately performed on the sacrificial substrate. The pixel isolation structures can then be attached to the backplane and the sacrificial substrate can be removed. This allows the formation of the pixel isolation structures to be isolated, the microLEDs to be tested early in the process, and the interface between the microLEDs and subsequent layers to be free of adhesive.