LED Electrode Structure with Reflective Layer for Light Extraction
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Solution Overview
Problem
Current light emitting diodes (LEDs) face limitations in light emitting efficiency and beam angle, particularly due to absorption of light by electrode layers and re-absorption of emitted light, which reduces overall performance.
Innovation Solution
The design incorporates a reflective layer with high reflectivity, positioned on top of an ohmic layer and extending to the semiconductor layers, along with a re-absorption preventive layer to minimize light absorption and enhance light extraction, using materials like Ag, Al, and Rh, and a specific electrode structure to improve light reflection and divergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional electrode layer structure is used, then the device structure is simple, but light emitting efficiency is reduced due to light absorption by electrode layers
Solution Approach 1:
The electrode layer is segmented into multiple functional sub-layers: a lower electrode layer for electrical contact, an insulating layer to prevent short circuits, and an upper electrode layer with reflective properties for light extraction. This segmentation allows each layer to perform its specific function optimally while resolving the contradiction between structural simplicity and light emitting efficiency.
Solution Approach 2:
An insulating layer is introduced as an intermediary between the lower and upper electrode layers. This intermediary layer prevents harmful electrical interaction (short circuits) while allowing the reflective upper electrode to improve light extraction. The insulating layer mediates between the conflicting requirements of electrical conductivity and optical performance.
2Reliability
If electrode layers are positioned to contact semiconductor layers, then electrical connection is achieved, but light re-absorption occurs reducing overall performance
Solution Approach 1:
The electrode structure is divided into separate functional layers: the lower electrode layer maintains electrical connection with the semiconductor layer, while the upper reflective electrode layer is positioned to intercept and reflect light before it can be re-absorbed. This segmentation allows simultaneous achievement of reliable electrical connection and reduced light re-absorption.
Solution Approach 2:
The upper electrode layer, which could potentially absorb light, is instead designed with high reflective properties to convert potential light absorption into beneficial light reflection. This transforms what would be a harmful effect (electrode light absorption) into a beneficial effect (enhanced light extraction and redirected light paths).
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
This configuration significantly enhances light emitting efficiency and widens the beam angle by effectively reflecting and diverging light, improving the performance of light emitting devices, packages, and lighting systems.
Implementation Method 1
the first electrode layer includes a reflective layer having an extension to the first conductive type semiconductor layer passed through an ohmic layer
Implementation Method 2
the first electrode layer includes an ohmic layer in contact with the first conductive type semiconductor layer
Data Source
AI summary
The present invention relates to a light emitting device, a light emitting device package, and a lighting device with the same.The light emitting device includes a light emitting structure including a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer, a second electrode layer formed on an underside of the light emitting structure connected to the second conductive type semiconductor layer electrically, a first electrode layer in contact with the first conductive type semiconductor layer passed through the second conductive type semiconductor layer and the active layer, and an insulating layer formed between the second electrode layer and the first electrode layer, between the second conductive type semiconductor layer and the first electrode layer, and between the active layer and the first electrode layer.