QD Color Conversion Micro-LED Subpixels Without RGB Placement
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Solution Overview
Problem
The fabrication of micro-LED panels with multiple color emission requires complex processes and stringent placement accuracy, limiting throughput and yield, and existing methods like pick-and-place steps are inefficient and prone to errors.
Innovation Solution
The use of subpixel isolation structures with color conversion materials and micro-lenses, where LEDs emit short wavelength light that is converted to longer wavelengths by these materials, eliminating the need for separate color LEDs and improving placement accuracy through reflective and light filter layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pick-and-place step is used to transfer micro-LED devices from donor substrates to destination substrate, then multiple color micro-LEDs can be integrated onto a single panel, but placement accuracy requirements (less than 1 μm) limit throughput and final yield
Solution Approach 1:
The invention segments the color generation function from the micro-LED device itself. Instead of requiring precisely placed different-colored micro-LEDs, monochrome micro-LEDs are used uniformly, and color conversion is achieved through separate color conversion layers deposited at specific pixel locations. This segmentation eliminates the need for high-precision placement of multiple LED types.
Solution Approach 2:
Color conversion layers (such as quantum dots or photoluminescent materials) serve as intermediaries between the monochrome micro-LED light source and the final displayed color. These intermediary layers convert the monochrome light to desired colors, replacing the need for precisely placed colored LEDs.
2Reliability
If separate fabrication processes on different substrates are used for micro-LEDs of different colors, then color-specific LED performance can be optimized, but the fabrication process complexity increases
Solution Approach 1:
The invention merges the fabrication of all micro-LEDs into a single monochrome fabrication process on a single substrate type. Instead of separately fabricating red, green, and blue micro-LEDs on different substrates, all micro-LEDs are fabricated uniformly, and color differentiation is achieved through subsequent color conversion layer deposition, significantly simplifying the fabrication process.
Solution Approach 2:
Monochrome micro-LEDs serve as universal light sources for all color pixels. The same micro-LED structure and material composition are used throughout the panel, with color functionality achieved through the universal application of color conversion layers, eliminating the need for color-specific LED fabrication.
3Ease of manufacture
If monochrome LEDs generate short wavelength light and color conversion agents convert to longer wavelengths, then selective color deposition can be performed, but the manufacturing process still requires high-resolution shadow masks or controllable printing
Solution Approach 1:
The invention uses transfer printing techniques where pre-fabricated color conversion patterns are copied onto the micro-LED substrate. Instead of directly depositing materials with high precision, master templates with color conversion patterns are created separately and then transferred, copying the desired color distribution onto the display panel.
Solution Approach 2:
Color conversion patterns are prepared in advance on separate master substrates or templates before being transferred to the micro-LED array. This preliminary fabrication of color patterns allows for optimization of the deposition process independently of the micro-LED fabrication, reducing the precision requirements during the final assembly step.
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 simplifies the manufacturing process, enhances color accuracy, and increases yield by integrating color conversion within the micro-LED panel structure, reducing the need for precise placement and allowing for more efficient production of micro-LED panels with improved color fidelity.
Implementation Method 1
The monochrome LEDs can generate relatively short wavelength light, e.g., purple or blue light, and the color conversion agents can convert this short wavelength light into longer wavelength light, e.g., red or green light for red or green pixels.
Implementation Method 2
micro-lenses disposed over each of the wells of the subpixels, the micro-lenses including a light filter material
Implementation Method 3
depositing a reflection material at an angle over a backplane, the backplane having LEDs disposed thereover
Data Source
AI summary
Embodiments of the present disclosure generally relate to LED pixels and methods of fabricating LED pixels. A device includes a backplane, at least three LEDs disposed on the backplane, subpixel isolation (SI) structures disposed defining wells of at least three subpixels, a reflection material is disposed on sidewalls and a top surface of the SI structures, at least three of the subpixels have a color conversion material disposed in the wells, an encapsulation layer disposed over the subpixel isolation structures and the subpixels, a light filter layer disposed over the encapsulation layer and micro-lenses disposed over the light filter layer and over each of the wells of the subpixels.