Light Emitting Cells with Via Holes for Enhanced Extraction
Solution Overview
Problem
Conventional high-voltage light emitting devices face challenges in heat radiation and luminance efficiency due to the use of sapphire substrates, which hinder light extraction and lead to reduced luminance efficiency.
Innovation Solution
The light emitting device incorporates a substrate with spaced-apart light emitting cells, featuring via holes and passivation layers that allow for electrical connections between cells and reflective structures to enhance light extraction by reflecting light at the substrate interface between cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sapphire substrate is used in a conventional horizontal high-voltage light emitting device, then the device structure is simple and easy to manufacture, but heat radiation is poor and luminance efficiency is reduced
Solution Approach 1:
The device is divided into multiple light emitting cells arranged in a specific pattern on the substrate, with spacing between cells that allows light extraction. This segmentation enables light to escape through the substrate interface between cells, improving luminance efficiency while maintaining manufacturing simplicity.
Solution Approach 2:
The invention utilizes the substrate interface between light emitting cells as an additional light extraction dimension. By arranging cells with spacing and using the substrate as a reflective interface, light is extracted not only from the top surface but also through the substrate, adding a dimensional aspect to light emission that improves overall efficiency.
2Loss of energy
If light emitting cells are spaced apart on the substrate, then light extraction at the substrate interface is improved, but the device complexity increases due to additional via holes and electrode connections
Solution Approach 1:
Adjacent light emitting cells are electrically connected by merging their electrode structures. The first electrode layer of one cell is electrically connected to the second electrode layer of an adjacent cell through via holes, combining multiple electrode functions into an integrated structure that reduces overall device complexity while enabling light extraction.
Solution Approach 2:
The via holes serve multiple functions: they provide electrical connection between adjacent cells, enable light extraction paths, and maintain structural integrity. This multi-functionality reduces the need for separate components, simplifying the overall device structure while improving luminance efficiency.
3Reliability
If via holes are created to connect electrodes between cells, then electrical connectivity is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The via holes are formed and electrode connections are established during the initial manufacturing process before final device assembly. This preliminary action ensures that electrical connectivity is built-in from the start, improving reliability while allowing standard manufacturing tolerances to be maintained without requiring ultra-precise post-processing.
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 improves luminance efficiency by allowing light reflection and extraction at the substrate interface, increasing the amount of light emitted and reducing absorption, thereby enhancing the overall performance of the light emitting device.
Implementation Method 1
a reflective layer is disposed on the second electrode layer in the structure of the light emitting cell to change a photon path, thereby improving luminance efficiency
Data Source
AI summary
A light emitting device includes a substrate; a plurality of light emitting cells disposed on the substrate to be spaced apart from one another, the light emitting cell having a via hole passing through the second conductive type semiconductor layer, the active layer and a part of the first conductive type semiconductor layer; a first electrode layer electrically connected to the first conductive type semiconductor layer at a bottom of the via hole; a second electrode layer disposed on the second conductive type semiconductor layer; and a first passivation layer, electrically separating the first electrode layer from the second electrode layer, wherein the first electrode layer of one light emitting cell is electrically connected to the second electrode layer of another light emitting cell adjacent to the one light emitting cell.