Light Emitting Device Side Wall Absorption
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) have a light-emitting area that is the same as their surface area, limiting their ability to achieve high current density and improved light efficiency in certain applications.
Innovation Solution
A light-emitting device with a light-absorbing layer surrounding the side wall of the light-emitting stack, configured to absorb a significant portion of the emitted light, allowing for a limited light-emitting area with high current density and enhanced light efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the light-emitting area is made equal to the surface area of the light-emitting stack, then the current spreading is improved, but the current density and light efficiency deteriorate
Solution Approach 1:
The light-emitting stack is divided into distinct functional regions: a light-emitting area that emits light and a light-absorbing area that absorbs light. This segmentation allows current to spread across the entire stack surface while confining high current density to the smaller light-emitting area, thus resolving the contradiction between current spreading and current density
Solution Approach 2:
A light-absorbing layer is introduced as an intermediary component surrounding the light-emitting stack. This layer absorbs light that would otherwise escape laterally, converting it to heat or re-emitting it in useful directions. The light-absorbing layer enables the stack to maintain a large current-spreading area while achieving high current density in the confined light-emitting area by preventing light loss and improving overall light efficiency
2Area of stationary object
If the light-emitting area is increased to match the surface area, then the light emission coverage is improved, but the light efficiency deteriorates
Solution Approach 1:
The light-absorbing layer converts what would be wasted light energy (lateral light emission from the stack) into useful energy by absorbing it and potentially re-emitting it in useful directions or converting it to heat that can be managed. This transforms the harmful light loss into a beneficial effect, improving overall light efficiency while maintaining a large light-emitting area
Solution Approach 2:
The invention changes the optical parameters of the device by introducing a light-absorbing layer with specific absorption characteristics. This layer has high absorption coefficient for the wavelength range emitted by the stack, changing the overall optical behavior from one where light escapes in all directions to one where light is selectively absorbed and managed, thereby improving light efficiency
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
The light-absorbing layer design enables more than 50% of emitted light to be absorbed, focusing the remaining light for improved extraction and efficiency, thereby increasing the light-emitting area's effectiveness.
Implementation Method 1
a light-absorbing layer having a first portion surrounding the side wall and being configured to absorb 50% light toward the light-absorbing layer
Data Source
AI summary
This disclosure discloses a light-emitting chip comprises: a light-emitting stack, having a side wall, comprising an active layer emitting light; and a light-absorbing layer having a first portion surrounding the side wall and being configured to absorb 50% light toward the light-absorbing layer.