Phosphor Converter Layer for Micro-LED Optical Contrast
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Solution Overview
Problem
Micro-LEDs face low optical contrast between neighboring pixels when one pixel is on and another is off, leading to poor optical resolution and visibility of light patterns.
Innovation Solution
A phosphor converter layer with specific parameters, including phosphor particles of certain sizes and refractive indices, and a thin non-luminescent material coating, is applied to micro-LEDs to enhance optical contrast. The phosphor converter layer consists of phosphor particles with a D50 size between 1 μm and 10 μm, a thickness between 4 μm and 20 μm, and a refractive index matrix less than 1.5, along with a thin layer of non-luminescent material like Al2O3, applied using atomic layer deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a phosphor converter layer is applied to micro-LEDs, then optical contrast is improved, but device complexity increases
Solution Approach 1:
The patent applies a composite phosphor converter layer consisting of phosphor particles embedded in a matrix material with specific refractive index properties. This composite structure enables enhanced optical contrast through controlled light scattering and absorption, while the matrix provides mechanical stability. The specific composition (phosphor particles with D50 1-10 μm in a matrix with refractive index 1.3-1.5) creates optimal optical contrast ratios greater than 1:300 between adjacent pixels.
Solution Approach 2:
The patent optimizes multiple parameters of the phosphor converter layer to achieve high optical contrast: phosphor particle size (D50: 1-10 μm), layer thickness (4-20 μm), and matrix refractive index (1.3-1.5). By carefully controlling these parameters, the solution achieves optical contrast ratios greater than 1:300 while maintaining a relatively simple single-layer structure that can be integrated into existing micro-LED fabrication processes.
2Measurement precision
If phosphor particles with specific size range are used, then optical resolution is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a phosphor particle size range (D50: 1-10 μm) that optimizes optical resolution by controlling light scattering behavior. This size range is large enough to provide sufficient scattering for high contrast but small enough to maintain uniformity across the display. The patent also specifies layer thickness (4-20 μm) to ensure complete light absorption while maintaining manufacturing feasibility with standard deposition techniques.
Solution Approach 2:
The patent applies the phosphor converter layer with uniform properties across the entire micro-LED array, ensuring consistent optical resolution throughout the display. The specific particle size distribution and layer thickness are maintained uniformly to achieve consistent optical contrast ratios greater than 1:300 across all pixels, while the relatively宽 ranges provided facilitate manufacturing tolerances.
3Loss of energy
If phosphor converter layer with specific thickness is applied, then light extraction is improved, but mechanical stability may be compromised
Solution Approach 1:
The patent uses a composite structure where phosphor particles are embedded in a matrix material that provides both optical functionality and mechanical support. The matrix material with refractive index 1.3-1.5 enhances light extraction through refractive index matching while providing mechanical stability. The layer thickness of 4-20 μm is sufficient for complete light absorption but thin enough to maintain substrate support and mechanical integrity.
Solution Approach 2:
The patent optimizes the phosphor converter layer thickness to 4-20 μm, which provides sufficient path length for complete light absorption and high extraction efficiency while remaining thin enough to maintain mechanical stability. The matrix refractive index (1.3-1.5) is specifically selected to enhance light extraction through optical impedance matching while the composite structure maintains mechanical robustness.
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
The solution significantly improves optical contrast, achieving ratios greater than 1:300, enhancing the visibility of light patterns and reliability for applications like automotive lighting, with improved mechanical stability and light extraction.
Implementation Method 1
a phosphor converter layer disposed on the micro-LED, the phosphor converter layer comprising a plurality of phosphor particles
Implementation Method 2
a thin layer of non-luminescent material coating on the phosphor particles
Implementation Method 3
a refractive index matrix less than 1.5
Data Source
AI summary
Embodiments include a device having a micro-LED that includes at least two, individually addressable light emitting diodes on a same substrate; a phosphor converter layer disposed on the micro-LED, the phosphor converter layer including phosphor particles having a D50 of greater than 1 μm and less than 10 μm.