Micro LED Display Panel Reflector Layout for Higher Light Efficiency
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Solution Overview
Problem
The light efficiency of micro light emitting diodes (LEDs) in micro LED display apparatuses is low due to the low reflectivity of the materials used in the electrodes, which reduces the transmittance of light emitted by the micro light-emitting elements.
Innovation Solution
A display panel design that includes a reflector with higher reflectivity than the electrode, made of metals like silver or aluminum, positioned on the electrode and covering the side surfaces of the micro light-emitting elements to enhance light reflectivity and transmittance, along with a method of manufacturing that involves eutectic bonding and patterning layers to optimize the contact length between the reflector and the micro light-emitting elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a micro LED display apparatus uses conventional electrode materials, then the device structure is simple and manufacturing is easier, but the light efficiency is low due to low reflectivity
Solution Approach 1:
The patent divides the reflective surface into two distinct components: the first electrode with moderate reflectivity and the second electrode with high reflectivity. This segmentation allows each electrode to serve a specific function - the first electrode for electrical connection and the second electrode for light reflection - thereby resolving the contradiction between structural simplicity and light efficiency.
Solution Approach 2:
The patent applies local quality by making different parts of the electrode structure have different reflectivity properties. The first electrode material (e.g., ITO) provides moderate reflectivity for electrical connection, while the second electrode material (e.g., Al, Ag, or Mo) provides high reflectivity specifically for light emission enhancement, optimizing performance at each location.
2Illumination intensity
If the reflector covers a larger area of the micro light-emitting element, then light reflectivity increases, but the contact length becomes too long causing manufacturing difficulties
Solution Approach 1:
The patent optimizes the contact length parameter to a specific range (0.1-5 μm) through precise control of the pixel-defining layer thickness and patterning process. This parameter optimization ensures sufficient light reflection while maintaining manufacturability through eutectic bonding, resolving the contradiction between light reflectivity and manufacturing precision.
3Reliability
If the first electrode material is changed to achieve eutectic bonding with micro LED, then bonding reliability improves, but reflectivity decreases
Solution Approach 1:
The patent segments the electrode function into two separate layers: the first electrode (e.g., ITO) optimized for eutectic bonding with micro LED chips, and the second electrode (e.g., Al, Ag, Mo) optimized for high reflectivity. This segmentation resolves the contradiction by allowing each layer to excel at its specific function without compromise.
Solution Approach 2:
The patent uses composite material structure with two different electrode materials stacked together. The first electrode material provides bonding compatibility with micro LED, while the second electrode material provides high reflectivity, creating a composite structure that achieves both bonding reliability and light efficiency.
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 increases the light reflectivity and transmittance of the micro light-emitting elements, improving the overall light efficiency of the display panel and reducing power consumption.
Implementation Method 1
a reflector disposed on the first electrode and covering at least a portion of a side surface of the micro light-emitting element... the reflector may have a first reflectivity
Implementation Method 2
the first electrode and the micro light-emitting element may be electrically connected to each other by eutectic bonding
Data Source
AI summary
A display panel includes a substrate, a first electrode disposed on the substrate, a pixel-defining layer disposed on the first electrode and including an opening exposing at least a portion of the first electrode, a micro light-emitting element electrically connected to the first electrode, and a reflector disposed on the first electrode and covering at least a portion of a side surface of the micro light-emitting element.