Stacked Electrode Structure for Light Extraction and Oxidation Resistance
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Solution Overview
Problem
High reflectivity materials like aluminum and silver used in light-emitting devices are prone to oxidation, leading to increased contact resistance and reduced current supply, which in turn increases drive voltage.
Innovation Solution
A stacked electrode structure is used, where a conductive film made of a refractory metal material, such as titanium nitride, is layered over a high reflectivity material to form a mixture layer with metal oxide, maintaining low contact resistance and high reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a material with high reflectivity such as aluminum or silver is used for an electrode, then light extraction efficiency is improved, but contact resistance increases due to oxidation
Solution Approach 1:
The patent applies composite materials by stacking a refractory metal material layer over a high-reflectivity material layer (aluminum or silver). This composite structure combines the high reflectivity of aluminum/silver with the oxidation resistance of refractory metals, allowing the system to maintain both low contact resistance and high light extraction efficiency simultaneously.
Solution Approach 2:
The refractory metal material serves as an intermediary layer between the high-reflectivity material and the environment (oxygen). This intermediary layer protects the aluminum or silver from oxidizing while allowing the system to maintain its electrical and optical properties.
2Illumination intensity
If a material with high reflectivity such as aluminum or silver is used for an electrode, then light extraction efficiency is improved, but drive voltage increases due to oxidation
Solution Approach 1:
The stacked composite structure of refractory metal over high-reflectivity material prevents oxidation of the aluminum or silver layer, thereby maintaining low contact resistance and preventing increase in drive voltage while preserving high light extraction efficiency.
Solution Approach 2:
The refractory metal layer is applied beforehand to cushion or protect the high-reflectivity material from oxidation before it can occur. This preventive measure ensures that the electrical properties remain stable and drive voltage does not increase.
3Illumination intensity
If aluminum or silver is used as an anode in a top emission panel, then high reflectivity in visible light is achieved, but the conductive film is easily oxidized when a layer containing oxygen is formed over it
Solution Approach 1:
The patent creates a composite electrode structure where a refractory metal material layer is stacked over the aluminum or silver layer. This composite structure maintains the high reflectivity of the bottom layer while the top refractory metal layer provides oxidation resistance, allowing oxygen-containing layers to be formed over the electrode without oxidizing the aluminum or silver.
Solution Approach 2:
The refractory metal layer acts as an intermediary barrier between the oxygen-containing environment and the aluminum/silver layer, preventing direct contact and oxidation of the high-reflectivity material while allowing the system to maintain its optical and electrical properties.
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 enhances light extraction efficiency and maintains low contact resistance, resulting in improved luminance and reduced drive voltage in light-emitting devices.
Implementation Method 1
a material with high reflectivity such as aluminum or silver is easily oxidized and gets close to an insulator property after oxidizing
Implementation Method 2
The light extraction efficiency can be increased by using reflection at the other electrode effectively
Implementation Method 3
a light-emitting element having a light-emitting substance provided between a pair of electrodes, and light from the light-emitting substance is extracted
Data Source
AI summary
It is an object of the present invention to provide a light-emitting device in which, even when a material with high reflectivity such as aluminum is used for an electrode, a layer containing oxygen can be formed over the electrode without increasing contact resistance and a manufacturing method thereof. According to the present invention, a feature thereof is a light-emitting element having an electrode composed of a stacked structure where a conductive film having high reflectivity such as aluminum, silver, and an alloy containing aluminum or an alloy containing silver, and a conductive film composed of a refractory metal material is provided over the conductive film, or a light-emitting device having the light-emitting element.