LED Light Extraction via Vertical Spacing and Transparent Conductive Layers
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) face challenges in achieving high light extraction efficiency due to the absorption of reflected light by the active layer, leading to reduced output and efficiency.
Innovation Solution
The design incorporates a substrate with high light transmittance and a space between the light emitting structure layer and the substrate, along with a transparent conductive layer, to guide light emitted from the active layer to the outside, enhancing extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the light emitting structure layer is disposed close to the substrate, then the device structure is compact, but light extraction efficiency is reduced due to absorption by the active layer
Solution Approach 1:
The patent introduces a vertical spacing dimension between the light emitting structure layer and substrate, transitioning from a planar close-contact structure to a vertically separated structure. This dimensional change allows light to be extracted through the transparent substrate without being absorbed by the active layer, thereby improving light extraction efficiency while maintaining structural integration through connection elements.
Solution Approach 2:
The patent employs transparent connection elements (such as transparent adhesive layers or support structures) as intermediaries to maintain electrical and mechanical connection between the light emitting structure layer and substrate while allowing light transmission. This intermediary structure enables both structural support and optical transparency, resolving the contradiction between structural integrity and light extraction.
2Illumination intensity
If a transparent conductive layer is added between the substrate and light emitting structure layer, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The transparent conductive layer serves multiple functions simultaneously: it provides electrical connection between the light emitting structure layer and substrate, maintains mechanical support, enables light transmission, and facilitates heat dissipation. By combining multiple functions into a single layer, the patent improves light extraction efficiency without proportionally increasing device complexity.
Solution Approach 2:
The patent uses composite transparent conductive materials (such as transparent conductive oxides like ITO or AZO) that combine optical transparency with electrical conductivity. This composite material property allows the layer to simultaneously achieve light transmission for improved extraction efficiency and electrical conduction for device operation, while maintaining a relatively simple single-layer structure.
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 improves light extraction efficiency by allowing light to be directed outward, increasing the overall output of the LED device.
Implementation Method 1
a transparent conductive layer is disposed between the substrate and the light emitting structure layer
Implementation Method 2
a light emitting structure layer disposed above the substrate at a distance from the substrate and electrically connected to the first contact layer, the light emitting structure layer comprising a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer
Implementation Method 3
a space is formed between the substrate and the light emitting structure layer
Data Source
AI summary
A light emitting device includes a substrate, at least one electrode, a first contact layer, a second contact layer, a light emitting structure layer, and an electrode layer. The electrode is disposed through the substrate. The first contact layer is disposed on a top surface of the substrate and electrically connected to the electrode. The second contact layer is disposed on a bottom surface of the substrate and electrically connected to the electrode. The light emitting structure layer is disposed above the substrate at a distance from the substrate and electrically connected to the first contact layer. The light emitting structure layer includes a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer. The electrode layer is disposed on the light emitting structure layer.