LED Encapsulation Structure for Higher Light Extraction in Dense Arrays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optoelectronic devices with light-emitting diodes, such as 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 optional conformal dielectric layers, along with lenses and angular filters, to enhance light extraction efficiency by optimizing refractive indices and structural configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If light-emitting diodes are arranged closely together to increase device density, then productivity and compactness are improved, but light extraction efficiency deteriorates due to photon absorption by adjacent diodes
Solution Approach 1:
An encapsulation layer with optimized refractive index (between 1.3 and 1.6) is introduced as an intermediary between adjacent light-emitting diodes. This encapsulation layer acts as a mediator that reduces optical coupling and photon absorption between neighboring diodes, allowing higher 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 2.0-3.0), creating an optical gradient that minimizes total internal reflection and photon trapping.
2Loss of energy
If encapsulation block thickness is increased to improve light extraction, then light extraction efficiency is improved, but device complexity and manufacturing precision requirements increase
Solution Approach 1:
The refractive index parameter of the encapsulation layer is optimized to be between 1.3 and 1.6, which creates favorable optical conditions for light extraction. This parameter optimization allows the use of thinner encapsulation layers (reducing manufacturing precision requirements) while still achieving high light extraction efficiency. The specific refractive index range is chosen to maximize the contrast with adjacent structures and minimize photon trapping, thereby reducing the critical thickness requirement.
3Loss of energy
If refractive index of encapsulation block is optimized to improve light extraction, then light extraction efficiency is improved, but device complexity increases due to additional material selection and processing
Solution Approach 1:
The encapsulation layer is applied locally around each light-emitting diode or group of diodes, with the refractive index optimized specifically for the optical interface requirements. This local quality approach allows different regions of the device to have tailored optical properties, improving light extraction where needed while keeping other areas simpler. The encapsulation layer can be selectively applied only where optical coupling needs to be managed, rather than uniformly across the entire device.
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 unwanted 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
the refractive index of the dielectric layer being comprised between 1.3 and 1.6
Data Source
AI summary
An optoelectronic device including a support including a face; light-emitting diodes lying on the face and comprising 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.