Wavelength-Converting Pixel Grid for Low-Crosstalk Micro-LED Arrays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In manufacturing arrays of individually addressable micro-LEDs, optical crosstalk between pixels is a significant issue due to the narrow and deep gaps between phosphor layers, making it difficult and costly to fill these gaps with reflective materials, and photoresist grids used for patterning can deteriorate quickly, reducing the lifespan of the device.
Innovation Solution
A method involving the formation of a grid structure using photoresist blocks with narrow gaps, which are filled with a reflective material to create a network of walls, allowing for the independent manufacturing of wavelength-converting pixel arrays that can be mounted over LEDs, minimizing crosstalk and using economically favorable materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single phosphor layer is applied over the entire LED array, then manufacturing cost is reduced, but optical crosstalk between pixels occurs
Solution Approach 1:
The phosphor layer is segmented into individual pixel-sized regions, with each micro-LED having its own dedicated phosphor layer. This segmentation prevents optical crosstalk between adjacent pixels while maintaining cost-effectiveness through batch processing techniques.
2Object-generated harmful factors
If phosphor layers are separated by narrow gaps to reduce crosstalk, then optical isolation is improved, but filling the gaps with reflective material becomes difficult and expensive
Solution Approach 1:
A photoresist grid structure is formed beforehand to define the phosphor layer regions and gap locations. The photoresist blocks serve as masks during phosphor deposition, automatically defining the narrow gaps without requiring subsequent complex filling operations. This preliminary structuring simplifies the overall manufacturing process.
3Manufacturing precision
If photoresist grid is used to pattern phosphor layers, then manufacturing precision is improved, but device lifetime is reduced due to photoresist deterioration
Solution Approach 1:
The photoresist grid is used only during the manufacturing process to define patterns, then completely removed after serving its purpose. The final device structure consists only of the LED array, phosphor layers, and encapsulant material, with no remaining photoresist components that could deteriorate over time.
Solution Approach 2:
The photoresist grid serves as a temporary, disposable patterning tool that is discarded after manufacturing. This approach allows high-precision patterning during fabrication while ensuring the final product contains only durable, long-lived materials suitable for extended operation.
4Area of stationary object
If micro-LEDs are closely packed to reduce spacing, then device compactness is improved, but optical crosstalk between adjacent pixels increases
Solution Approach 1:
Each micro-LED pixel is equipped with its own localized phosphor layer and encapsulant material, creating pixel-specific optical confinement. This local structuring ensures that even in closely-packed arrangements, light from each pixel is contained and converted to wavelength within that pixel's region, preventing crosstalk to adjacent pixels.
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 enables the production of closely-packed wavelength-converting pixel arrays at a lower cost with minimal crosstalk, using suitable materials to form a reflective grid that surrounds each pixel, enhancing the longevity and performance of the light-emitting device.
Implementation Method 1
The photoresist blocks are removed from the grid structure, to expose an array of cavities or empty cells defined by the walls of the grid
Implementation Method 2
it is then necessary to fill these gaps by a reflecting material to ensure that any light exiting the side faces of the phosphor layer covering one LED will not enter the side faces of an adjacent phosphor layer
Implementation Method 3
The primary purpose of such a phosphor is wavelength conversion
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention describes a method of manufacturing a wavelength- converting pixel array structure (1), which method comprises the steps of forming an array of photoresist blocks (10), wherein the photoresist blocks (10) are separated by gaps (G), and wherein the position of a photoresist block (10) in the array of photoresist blocks (10) corresponds to the position of a light-emitting diode (20) in a light-emitting diode array (2); filling the gaps (G) around each photoresist block (10) with a filler material to form a grid (11); removing the photoresist blocks (10) to expose an array of cavities (C) in the grid (11); and filling each cavity (C) defined by the walls of the grid (11) with a wavelength-converting material to form the wavelength-converting pixels (12) of the wavelength-converting pixel array structure (1), wherein the wavelength-converting pixel array structure (1) is prepared in a recess (50) formed in a wafer. The invention further describes a method of manufacturing a light- emitting device (3).