LED Cell Interconnection Layout for Droop Suppression
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) face a droop phenomenon as current density increases, leading to decreased external quantum efficiency and obstructed improvement in luminous efficacy.
Innovation Solution
A light emitting diode structure is designed with first to fourth light emitting cells connected in series and parallel, featuring a substrate with semiconductor stacks, electrode pads, and current blocking layers to manage current density and prevent droop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If current density is increased to improve light output intensity, then light output intensity increases, but external quantum efficiency decreases due to droop phenomenon
Solution Approach 1:
The light emitting diode is divided into multiple light emitting cells (first to fourth light emitting cells) that are connected in series and parallel configurations. This segmentation allows the total current to be distributed across multiple cells, reducing the current density in each individual cell while maintaining the overall light output intensity. The series connection ensures uniform current spreading across cells, preventing droop phenomenon in each cell.
2Productivity
If current density is increased to improve luminous efficacy, then light output increases, but droop phenomenon increases causing light loss
Solution Approach 1:
The LED structure is segmented into multiple light emitting cells with series and parallel connections. This segmentation reduces current density in each cell, suppressing droop phenomenon and minimizing light loss while maintaining high luminous efficacy through efficient current distribution.
Solution Approach 2:
Current blocking layers are strategically positioned between light emitting cells to control and optimize current distribution locally. This ensures uniform current spreading across each cell while preventing current concentration that would cause droop and light loss, thereby maintaining high luminous efficacy.
3Loss of energy
If series connection is used to reduce current density, then current density decreases and droop is suppressed, but device complexity increases
Solution Approach 1:
Multiple light emitting cells are merged into a single integrated LED structure with shared substrate, electrode pads, and current blocking layers. This merging approach achieves series connection for droop suppression while sharing common components reduces the overall device complexity compared to completely separate cells.
Solution Approach 2:
The electrode pads and current blocking layers serve multiple functions: they electrically connect multiple light emitting cells in series, provide current distribution, and suppress droop phenomenon across all cells. This multi-functionality reduces the need for additional specialized components, simplifying the overall device structure.
4Stability of the object's composition
If parallel connection is used to ensure uniform current spreading, then current uniformity improves, but device complexity increases
Solution Approach 1:
The parallel connection structure is merged with the series connection in an integrated configuration where light emitting cells are interconnected through shared electrode pads and current blocking layers. This unified structure achieves uniform current spreading while minimizing the number of discrete connection 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
The proposed structure enhances luminous efficacy by reducing current density through series connection and ensuring uniform current spreading via parallel connection, thereby suppressing the droop phenomenon.
Implementation Method 1
A light emitting diode (LED) refers to a solid state light emitting device that converts electrical energy into light
Implementation Method 2
current blocking layers to manage current density and prevent droop
Data Source
AI summary
A light emitting diode including a substrate having a first area and a second area defined by an isolation groove line, a semiconductor stack disposed on the substrate and including a lower semiconductor layer, an upper semiconductor layer, an active layer, a first electrode pad electrically connected to the lower semiconductor layer, a second electrode pad electrically connected to the upper semiconductor layer, and a connecting portion electrically connecting the semiconductor stack disposed in the first and second areas to each other, and including a first portion, a second portion, and a third portion extending from a second distal end of the first portion, in which the isolation groove line is disposed between the first and second electrode pads and exposes the substrate, the first portion extends along a first direction substantially parallel to an extending direction of the isolation groove line, and the second and third portions extend in a second direction crossing the first direction.