LED Reflective Layer Design for Light Extraction
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Solution Overview
Problem
Conventional light-emitting diodes face issues with light extraction efficiency due to energy absorption and brightness reduction, as well as vulnerability to corrosion and electrical failure from metallic reflective layers, especially under overdriving operations.
Innovation Solution
A light-emitting diode design featuring a reflective layer made of metal or ceramic materials, such as aluminum, silver, or rhodium, positioned between the current blocking and second type semiconductor layers, with transparent conductive current spreading layers to minimize light absorption and exposure to environmental corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a metallic reflective layer is used to reflect light, then light extraction efficiency is improved, but the reflective layer is vulnerable to corrosion from air or water vapor resulting in broken circuits and electrical failure
Solution Approach 1:
The patent employs a composite structure consisting of a metallic reflective layer combined with a protective dielectric layer. This composite material approach allows the system to simultaneously achieve high light extraction efficiency from the metallic layer while obtaining corrosion resistance and electrical stability from the dielectric protective layer, thereby resolving the contradiction between productivity and reliability
Solution Approach 2:
The dielectric protective layer serves as an intermediary between the metallic reflective layer and the external environment (air and water vapor). This intermediary layer prevents direct contact between the corrosive environment and the metallic layer, thus protecting the circuit from corrosion while maintaining the light reflection function, effectively resolving the contradiction between light extraction efficiency and electrical failure resistance
2Productivity
If a metallic reflective layer is used, then light reflection is enhanced, but under overdriving operation the metallic material diffuses into the current spreading layer increasing surface resistance and damaging the structure
Solution Approach 1:
The patent uses a composite structure of metallic reflective layer and dielectric protective layer to prevent metal diffusion. The dielectric layer acts as a barrier that stops metallic material from diffusing into the current spreading layer during overdriving operation, thereby maintaining both light reflection efficiency and structural integrity
Solution Approach 2:
The dielectric protective layer functions as an intermediary barrier between the metallic reflective layer and the current spreading layer. This intermediary prevents direct interaction and diffusion between the metallic material and the semiconductor layer, thus resolving the contradiction between light reflection efficiency and structural integrity under overdriving conditions
3Productivity
If light passes through the second type semiconductor layer, current blocking layer and current spreading layer, then the light energy is absorbed and brightness is reduced
Solution Approach 1:
Instead of allowing light to pass through multiple absorbing layers, the patent inverts the approach by placing a reflective layer to bounce light back through the light-emitting layer. This inversion transforms the light path from transmission mode to reflection mode, enabling light to exit through the same side it entered, thereby improving light extraction efficiency and reducing energy loss from absorption
Solution Approach 2:
The reflective layer ensures continuous useful action by repeatedly reflecting light back through the active region, maximizing the probability of light extraction before absorption occurs. This continuous reflection process enhances the overall light output efficiency while minimizing energy loss to absorption in the semiconductor and current spreading layers
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 enhances light extraction efficiency and reliability by reducing light absorption and preventing corrosion, allowing the light-emitting diode to withstand overdriving operations without structural damage.
Implementation Method 1
when a light B emits from the light-emitting layer 120, the light B may penetrate the second type semiconductor layer 130, the current blocking layer 170 and current spreading layer 140, and then be reflected by the reflective layer 180
Implementation Method 2
The current spreading layer 140 covers the second type semiconductor layer 130
Implementation Method 3
a light-emitting layer 120 sandwiched between the first type semiconductor layer 110 and the second type semiconductor layer 130
Data Source
AI summary
The disclosure provides a light-emitting diode which includes a first semiconductor layer, a light-emitting layer, a second semiconductor layer, a reflective layer, a current blocking layer and a current spreading layer. The light-emitting layer is positioned on the first semiconductor layer, and the second semiconductor layer is positioned on the light-emitting layer. The reflective layer is positioned on a part of the second semiconductor layer, so as to expose another part of the second semiconductor layer. The current blocking layer covers the reflective layer, and the current spreading layer covers the exposed second semiconductor layer and current blocking layer.