Transparent Insulating Layer for Light Extraction in LED Devices
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Solution Overview
Problem
Conventional light-emitting devices face limitations in luminous efficacy and brightness due to the lack of an effective transparent insulating layer that enhances light extraction efficiency.
Innovation Solution
A light-emitting device is designed with a transparent insulating layer between the light-emitting stack and the electrode structure, featuring a protruding extension part that improves light transmission and reduces surface irregularities, using materials like aluminum zinc oxide (AZO) with high refractive index and transmittance, and a specific electrode configuration for enhanced ohmic contact and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional light-emitting device structure is used without a transparent insulating layer, then the device structure is simpler, but the light extraction efficiency is lower and luminous intensity is reduced
Solution Approach 1:
A transparent insulating layer is introduced as an intermediary component between the light-emitting stack and the electrode structure. This layer has a refractive index between 1.5 and 2.5, which is higher than the surrounding media, enabling it to act as an optical mediator that enhances light extraction efficiency through refractive index matching and reduced total internal reflection, thereby increasing luminous intensity without significantly complicating the manufacturing process
Solution Approach 2:
The transparent insulating layer changes the optical parameters of the device by providing a specific refractive index range (1.5-2.5) that optimizes light extraction. This parameter change in the refractive index profile allows for better impedance matching between different layers, improving light coupling and extraction efficiency, which directly addresses the luminous intensity issue while maintaining structural feasibility
2Reliability
If the transparent insulating layer covers the entire electrode structure including the extension electrode, then the insulation is more complete, but the light extraction efficiency is reduced due to blocking light paths
Solution Approach 1:
The transparent insulating layer is selectively positioned to cover only specific regions of the electrode structure - specifically the first electrode and its immediate extensions - while leaving other areas exposed. This local quality approach ensures adequate insulation where electrically critical while preserving light extraction pathways in regions where optical performance is prioritized, thus balancing insulation completeness with light extraction efficiency
Solution Approach 2:
The electrode structure is segmented into different functional zones: the first electrode region that requires insulation coverage, and the extension electrode regions that benefit from light exposure. The transparent insulating layer is correspondingly segmented in its coverage, creating distinct insulated and non-insulated zones that optimize both electrical reliability and optical performance in different spatial locations
3Reliability
If the surface area of the first electrode is increased to improve ohmic contact, then the electrical contact is better, but the light extraction efficiency is reduced due to larger electrode shadowing
Solution Approach 1:
The transparent insulating layer acts as an optical intermediary that compensates for the light-blocking effect of a larger first electrode. By providing a refractive index match and reducing total internal reflection at interfaces, it offsets the shadowing loss caused by the enlarged electrode area, allowing the electrode to be sufficiently large for good ohmic contact while maintaining light extraction efficiency through the insulating layer's optical mediation
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 solution results in a 6-7% increase in luminous intensity and improved light extraction efficiency, with the transparent insulating layer achieving transmittance greater than 98% and sheet resistance greater than 10Ω/□, leading to higher brightness and efficiency compared to conventional devices.
Implementation Method 1
a transparent insulating layer between the light-emitting stack and the electrode structure, wherein the transparent insulating layer comprises a first part and an extension part protruding from the first part toward the edge of the light-emitting device
Implementation Method 2
using materials like aluminum zinc oxide (AZO) with high refractive index and transmittance
Implementation Method 3
an electrode structure on the light-emitting stack and comprising a first electrode and an extension electrode protruding from the first electrode toward an edge of the light-emitting device
Implementation Method 4
The principle of light emission of a light-emitting diode (LED) is different from that of an incandescent light
Data Source
AI summary
A light-emitting device is provided. The light-emitting device comprises: a light-emitting stack having an active layer; an electrode structure on the light-emitting stack and comprising a first electrode and an extension electrode protruding from the first electrode toward an edge of the light-emitting device in a first extending direction; a transparent insulating layer between the light-emitting stack and the electrode structure, wherein the transparent insulating layer comprises a first part and an extension part protruding from the first part toward the edge of the light-emitting device in a second extending direction; wherein a surface area of a surface of the first electrode distal from the transparent insulating layer is smaller than a surface area of a surface of the transparent insulating layer distal from the light-emitting stack, the first electrode is right above the first part, and a part of the extension electrode is right above the extension part.