Tapered Substrate Light Extraction for LED Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light-emitting devices face challenges in maintaining high light extraction efficiency when downsized or thinned, as they struggle to effectively reflect and extract light due to absorption and scattering issues with the substrate and sidewall materials.
Innovation Solution
The design incorporates a light-emitting device with a tapered portion on the side surface of the substrate and a low-refractive-index layer between the light-emitting element and the sidewall, which reduces light absorption and scattering, enhancing light extraction efficiency by reflecting light upward and utilizing a low-refractive-index material like air or vacuum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the device is downsized or thinned, then the device size is reduced, but light extraction efficiency deteriorates due to increased absorption and scattering
Solution Approach 1:
The substrate side surface is formed with a tapered portion having a curved surface that gradually decreases in width from the light-emitting element side toward the sidewall. This curved geometry redirects light traveling toward the sidewall back into the light-emitting element, reducing light loss and improving extraction efficiency even in compact device configurations.
Solution Approach 2:
The invention addresses light extraction in the lateral dimension by adding a tapered portion on the substrate side surface. This dimensional modification creates additional light reflection paths that compensate for the reduced device size, allowing efficient light extraction without increasing overall device volume.
2Ease of manufacture
If conventional substrate and sidewall materials are used, then manufacturing is simplified, but light absorption and scattering increase, reducing light extraction efficiency
Solution Approach 1:
The invention modifies the geometric parameters of the substrate side surface by introducing a tapered portion with specific angle and depth parameters. This geometric parameter change alters light propagation paths without requiring material substitution, thereby reducing absorption and scattering losses while maintaining manufacturing simplicity.
3Device complexity
If light is directed toward the sidewall, then device structure is simplified, but light is lost through absorption and scattering by the sidewall
Solution Approach 1:
The tapered portion on the substrate side surface acts as a reflective feature that redirects light away from the sidewall. The curved surface geometry of the taper reflects light back into the light-emitting element, preventing light loss at the sidewall interface while maintaining a relatively simple device structure without additional components.
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, ensuring high performance even in compact or thin device forms by minimizing absorption and optimizing light reflection and distribution.
Implementation Method 1
a low-refractive-index layer that is located between the light-emitting element and the sidewall and has a smaller refractive index than the second substrate
Implementation Method 2
light emitted from a light-emitting layer of the element is likely to be reflected upward since an angle defined between the light traveling in the element mounting substrate toward the outside and a surface of the tapered portion of the element mounting substrate decreases
Data Source
AI summary
A light-emitting device includes a case including a first substrate and a sidewall on the first substrate, a light-emitting, element that is mounted on the first substrate in a region surrounded by the sidewall and includes a second substrate and a crystal layer, the light-emitting element being formed rectangular in a plane viewed in a direction perpendicular to the first substrate, and a low-refractive-index layer that is located between the light-emitting element and the sidewall and has a smaller refractive index than the second substrate. A side surface along a longitudinal direction of the second substrate is provided with a tapered portion on a side of the first substrate.