Multilayered OLED Anode with Silver Alloy and Metal Oxide
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Solution Overview
Problem
Conventional organic light emitting diodes face issues with decreased luminous efficiency due to a single layer anode's reduced work function over time, and the use of silver or silver alloys for improved reflectance is hindered by poor adhesion to substrates and susceptibility to moisture-related degradation.
Innovation Solution
A multilayer pixel electrode structure is introduced, comprising a first layer of metal oxide, a second layer of silver alloy with specific lanthanide and actinide series elements, and a third layer of metal oxide, enhancing adhesion and reflectance without requiring additional adhesive materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If silver or silver alloy is used to form the anode to improve reflectance, then brightness of light is increased, but adhesion with substrate deteriorates and productivity is degraded
Solution Approach 1:
The anode is divided into multiple layers: a first metal oxide layer (50-200 nm) for substrate adhesion, a silver alloy layer (100-500 nm) for high reflectance, and a third metal oxide layer (50-200 nm) for protection and conductivity. This segmentation allows each layer to perform its specific function optimally without compromising the others.
Solution Approach 2:
The patent uses composite material structure combining metal oxide (such as ITO or IZO) with silver alloy. The metal oxide provides good adhesion to glass substrates and electrical conductivity, while the silver alloy provides high reflectance. This composite approach resolves the contradiction between achieving high brightness and maintaining ease of manufacture.
2Illumination intensity
If silver or silver alloy is used to form the anode to improve reflectance, then brightness of light is increased, but adhesion with substrate deteriorates
Solution Approach 1:
The anode is divided into multiple layers: a first metal oxide layer (50-200 nm) for substrate adhesion, a silver alloy layer (100-500 nm) for high reflectance, and a third metal oxide layer (50-200 nm) for protection and conductivity. This segmentation allows each layer to perform its specific function optimally without compromising the others.
Solution Approach 2:
The metal oxide layers act as intermediary layers between the glass substrate and the silver alloy layer. These intermediary layers provide good adhesion to both the substrate and the silver alloy, preventing the silver from detaching while maintaining the high reflectance properties.
3Device complexity
If single layer anode is used, then structure is simple, but work function decreases over time causing luminous efficiency to decrease
Solution Approach 1:
The anode is divided into multiple layers: a first metal oxide layer (50-200 nm) for substrate adhesion, a silver alloy layer (100-500 nm) for high reflectance, and a third metal oxide layer (50-200 nm) for protection and conductivity. This segmentation allows each layer to perform its specific function optimally without compromising the others.
Solution Approach 2:
The metal oxide layers are deposited before and after the silver alloy layer to preliminarily establish stable electrical properties and protect the silver from degradation. This preliminary protective action prevents the work function from decreasing over time, maintaining high luminous efficiency throughout the device's operational life.
4Illumination intensity
If silver or silver alloy is used to form the anode to improve reflectance, then brightness is increased, but susceptibility to moisture-related degradation increases
Solution Approach 1:
The patent acknowledges that silver is susceptible to moisture-related degradation but converts this potential harm into a benefit by enclosing the silver alloy layer between protective metal oxide layers. These protective layers act as barriers against moisture, preventing degradation while allowing the silver to provide high reflectance and brightness.
Solution Approach 2:
The metal oxide layers act as intermediary protective barriers between the silver alloy and the external environment (moisture). These intermediary layers prevent direct contact between moisture and the silver, thereby preventing degradation while maintaining the optical and electrical properties of the silver alloy layer.
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 multilayer structure improves productivity and reflectance, maintaining high luminance while preventing light loss and color tone changes, thus enhancing the overall performance of the organic light emitting diode.
Implementation Method 1
The anode using the silver or silver alloy has a relatively high reflectance so that brightness (luminance) of light generated in the emission layer may be further increased
Data Source
AI summary
An organic light emitting diode, which has a pixel electrode, the pixel electrode constructed with a first layer comprising metal oxide on the substrate; a second layer comprising silver alloyed with at least one metal selected from a group consisting of lanthanide series elements and actinide series elements on the first layer; and a third layer comprising metal oxide on the second layer. As such, there are provided the second layer comprising the silver alloy, and the first and third layer comprising the metal oxide and formed above and below the second layer so that adhesion of a silver alloy (e.g., ATD alloy) may be enhanced, and an anode having enhanced reflectance may also be provided by using silver with increased reflectance.