Stacked LED Light Emitting Parts for Higher Quantum Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current light emitting devices face challenges in achieving optimal light efficiency and extraction due to limitations in the stacking and electrical conductivity of semiconductor layers, leading to inefficient color mixing and quantum efficiency.
Innovation Solution
A light emitting device design featuring a stacked structure of multiple light emitting parts with specific semiconductor layers, conductive patterns, and passivation layers to enhance electrical conductivity and light extraction, including a unique configuration of metal patterns and via structures to improve ohmic contact and reduce delamination risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple light emitting parts are stacked to improve light efficiency, then light extraction is enhanced, but device complexity increases
Solution Approach 1:
The light emitting device is divided into multiple discrete light emitting parts (first, second, third light emitting parts) that are stacked vertically. Each part contains segmented functional layers (semiconductor layers, active layers, ohmic layers, metal patterns) that can be independently configured and optimized, allowing improved light efficiency through stacking while managing complexity through modular design
Solution Approach 2:
The patent transitions from a planar light emitting structure to a three-dimensional stacked configuration. By adding the vertical dimension with multiple light emitting parts stacked on top of each other, the device achieves enhanced light extraction and efficiency without merely scaling up the horizontal area, thus improving productivity while managing complexity through spatial optimization
2Reliability
If metal patterns are used to improve electrical conductivity, then ohmic contact is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
Metal patterns are formed on the semiconductor layers before final device assembly and stacking. This preliminary formation of conductive paths ensures proper ohmic contact is established in advance, allowing for quality control and alignment verification before the device is fully assembled, thereby reducing the stringency of precision requirements during final manufacturing
Solution Approach 2:
The metal patterns serve as intermediary conductive elements between the semiconductor layers and external electrical contacts. These intermediate metal structures (first and second metal patterns with first and second surfaces) facilitate ohmic contact by providing a dedicated conductive pathway, isolating the precision requirements from the final device assembly and allowing independent optimization of electrical connectivity
3Productivity
If semiconductor layers are stacked to achieve color mixing, then quantum efficiency improves, but light extraction efficiency decreases
Solution Approach 1:
The device segments the light emitting function into multiple discrete parts with different active layers, each potentially emitting different wavelengths. By stacking these segmented light emitting parts, the device achieves color mixing through spatial separation rather than wavelength conversion, maintaining quantum efficiency while enabling light extraction through the stacked structure
Solution Approach 2:
The patent resolves the color mixing versus light extraction contradiction by moving from a planar wavelength-mixing approach to a three-dimensional stacked configuration. Different light emitting parts are stacked vertically, allowing each part to emit light efficiently in its own plane while the stack as a whole achieves color mixing through the combination of multiple emission sources, thus improving light extraction efficiency while maintaining quantum 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 design achieves improved light efficiency and external quantum efficiency by optimizing the stacking of semiconductor layers and electrical conductivity, preventing color mixing and enhancing light extraction, thereby improving the overall performance of the light emitting device.
Implementation Method 1
a first via structure electrically coupling the second metal pattern and the common pad between the second metal pattern and the common pad
Implementation Method 2
a first light emitting part including a first-type semiconductor layer, a first active layer, a second-type semiconductor layer, and a first ohmic layer
Data Source
AI summary
A light emitting device including first, second, and third light emitting parts disposed near each other and each including a first-type semiconductor layer, a first active layer, and a second-type semiconductor layer, a first pad electrically coupled with the second-type semiconductor layer of the first light emitting part, a second pad electrically coupled with the second-type semiconductor layer of the second light emitting part, a third pad electrically coupled with the second-type semiconductor layer of the third light emitting part, and a common pad electrically coupled with the first-type semiconductor layer of the first, second, and third light emitting parts, in which, in a current density per light emitting part of about 20 A/cm2, one of the first, second, and third light emitting parts that is configured to emit light having the longest peak wavelength has a largest normalized external quantum efficiency.