LED Encapsulation Blocks With Air Gaps for Dense Array Light Extraction
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Solution Overview
Problem
Existing optoelectronic devices with light-emitting diodes, such as those using semiconductor microwires or nanowires, suffer from low light extraction efficiency due to a significant portion of photons not escaping, leading to absorption or trapping by adjacent diodes.
Innovation Solution
The implementation of an optoelectronic device design featuring light-emitting diodes with encapsulation blocks that are partially transparent, an electrically conductive layer, and interstices of air between adjacent diodes, along with a conformal dielectric layer and lenses, optimized for refractive indices between 1.3 and 2.2, to enhance light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If light-emitting diodes are arranged closely together to increase device density, then productivity and device compactness improve, but light extraction efficiency deteriorates due to adjacent diodes absorbing or trapping photons
Solution Approach 1:
An encapsulation layer with optimized refractive index (between 1.3 and 2.2) is introduced as an intermediary medium between adjacent light-emitting diodes. This layer acts as an optical mediator that reduces photon absorption and trapping between closely spaced diodes, enabling high device density while maintaining light extraction efficiency. The encapsulation layer refractive index is specifically chosen to be between that of air (1.0) and the semiconductor material (typically 2.5-3.5), creating optimal optical conditions for light extraction.
Solution Approach 2:
The refractive index of the encapsulation layer is optimized as a key parameter to resolve the contradiction. By adjusting the encapsulation layer refractive index to be between 1.3 and 2.2, the optical properties of the system are changed to minimize total internal reflection and photon trapping between adjacent diodes. This parameter optimization allows closely spaced diodes to coexist without significant optical interference, enabling both high density and high light extraction efficiency.
2Loss of energy
If encapsulation block thickness is increased to improve light extraction, then light extraction efficiency improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The encapsulation layer thickness is optimized to a specific range (1 μm to 30 μm) to achieve optimal light extraction efficiency while maintaining manufacturing feasibility. This thickness parameter is carefully chosen: thin enough to allow effective light extraction and avoid excessive absorption within the encapsulation layer itself, but thick enough to provide adequate optical isolation between adjacent diodes and ensure proper encapsulation. This optimized thickness range resolves the contradiction by providing sufficient light extraction performance without creating excessive manufacturing complexity.
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 design significantly increases the light extraction efficiency by allowing more photons to escape and reducing absorption, thereby improving the overall performance of the optoelectronic device.
Implementation Method 1
the refractive index of the encapsulation block covering at least one of the light-emitting diodes or one of the groups of light-emitting diodes is comprised between 1.3 and 1.6
Implementation Method 2
a fraction of the photons emitted within each light-emitting diode does not escape from the light-emitting diode
Implementation Method 3
the refractive index of the dielectric layer being comprised between 1.3 and 1.6
Implementation Method 4
reducing the proportion of the light emitted by a light-emitting diode that is absorbed/trapped by the adjacent light-emitting diodes
Data Source
AI summary
An optoelectronic device including a support including a face; light-emitting diodes lying on the face and including semiconductor elements in the form of wires, cones or truncated cones; for each light-emitting diode, an encapsulation block at least partially transparent to the radiation emitted by the light-emitting diodes and covering the light-emitting diode, the maximum thickness of the encapsulation block being comprised between 1 μm and 30 μm, interstices of air being present between the encapsulation blocks covering adjacent diodes; and an electrically conductive layer covering the encapsulation blocks, wherein the refractive index of the encapsulation block covering at least one of the light-emitting diodes is comprised between 1.3 and 1.6.