Micro LED Electrode Interface Structure for Lower Reflection Loss
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Solution Overview
Problem
Current micro LED elements face challenges in enhancing light extraction efficiency, which is crucial for improving the performance of display devices and electronic apparatuses.
Innovation Solution
A light-emitting device design featuring a first electrode, a light-transmitting second electrode, a first semiconductor layer, a second semiconductor layer, a light-emitting layer, and a light-transmitting portion with a refractive index structure that includes a tapered shape and uneven surface, optimizing the refractive index mismatch and light reflection to enhance light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional micro LED element structure is used, then the device is simple to manufacture, but light extraction efficiency is poor due to refractive index mismatch and light reflection at interfaces
Solution Approach 1:
The patent introduces an intermediate layer between the semiconductor layer and electrode that has a refractive index介于between the two. This intermediate layer acts as a mediator to gradually transition the refractive index, reducing the abrupt mismatch that causes light reflection. The intermediate layer enables smooth optical transition while maintaining electrical functionality, thereby improving light extraction efficiency without complicating the manufacturing process significantly.
Solution Approach 2:
The patent modifies the refractive index parameter by introducing materials with specific refractive index values between the semiconductor layer and electrode. By carefully selecting and controlling the refractive index of the intermediate layer, the patent optimizes light extraction efficiency. This parameter change approach allows systematic improvement of optical performance while maintaining manufacturing feasibility.
2Reliability
If the refractive index difference between the semiconductor layer and electrode is large, then electrical conductivity is improved, but light reflection increases and light extraction efficiency decreases
Solution Approach 1:
The intermediate layer serves as a dual-function mediator: electrically, it maintains conductivity pathways between the semiconductor and electrode; optically, it provides a gradual refractive index transition that minimizes reflection. This intermediary structure resolves the contradiction by decoupling the electrical and optical requirements through a multi-functional layer.
Solution Approach 2:
The patent employs composite material structures where the intermediate layer may combine multiple materials or have graded composition to achieve both good electrical conductivity and optimized refractive index. This composite approach allows simultaneous satisfaction of electrical reliability and optical efficiency requirements.
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 significantly improves light extraction efficiency by reducing light reflection at the interface between the semiconductor layer and the electrode, while also minimizing light loss through multiple reflections, thereby enhancing the overall performance of light-emitting devices.
Implementation Method 1
reducing light reflection at the interface between the semiconductor layer and the electrode
Implementation Method 2
a refractive index of the second electrode is lower than a refractive index of the second semiconductor layer and is higher than a refractive index of the light-transmitting portion
Data Source
AI summary
A light-emitting device includes: a first electrode; a second electrode has a light-transmitting property; a first semiconductor layer that is provided between the first electrode and the second electrode; a second semiconductor layer that is provided between the first semiconductor layer and the second electrode and is in contact with the second electrode; a light-emitting layer that is provided between the first semiconductor layer and the second semiconductor layer; and a light-transmitting portion provided on a side of the second electrode opposite to the second semiconductor layer, wherein light generated in the light-emitting layer is emitted from side of the second electrode, a refractive index of the second electrode is lower than a refractive index of the second semiconductor layer and is higher than a refractive index of the light-transmitting portion, and a surface of the second semiconductor layer in contact with the second electrode has an uneven structure.