Transparent Electrode Injection Layer for Light Emitting Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional metal-based transparent electrodes in light emitting devices compromise transparency and conductivity, leading to uneven brightness and reduced luminous efficiency when attempts are made to improve transparency by creating holes or perforations.
Innovation Solution
Incorporating a metal-doped alkali metal salt or metal-doped metal oxide injection layer between the transparent conducting layer and the light emitting layer, which enhances transmittance while maintaining high conductivity without the need for structural modifications like holes or perforations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional metal-based transparent electrodes are used, then conductivity is maintained, but transmittance decreases and transparency is compromised
Solution Approach 1:
The patent employs a composite electrode structure consisting of a transparent conducting oxide layer (such as ITO, IZO, or AZO) combined with a metal layer (such as Ag, Al, or Mo). This composite structure leverages the high transmittance properties of the transparent oxide and the high conductivity of the metal, achieving both improved transparency and maintained conductivity simultaneously. The multi-layer composite design resolves the contradiction by combining materials with complementary properties rather than relying on a single material that must compromise between these two attributes.
Solution Approach 2:
The patent introduces a gradient or patterned metal layer design where the metal distribution is optimized locally. In regions requiring higher transmittance, the metal layer is made thinner or more sparse, while in regions requiring higher conductivity, the metal layer is thicker or more dense. This local variation in material properties allows different parts of the electrode to optimize for their specific functional requirements, resolving the global contradiction between transmittance and conductivity.
2Illumination intensity
If holes or perforations are made in the metal-based transparent electrode to improve transparency, then transmittance increases, but brightness uniformity decreases and resistance increases
Solution Approach 1:
Instead of creating holes in a metal layer, the patent uses a composite structure where a transparent conducting oxide layer is combined with a continuous or near-continuous metal layer. The transparent oxide layer provides the necessary transmittance without requiring physical holes, while the continuous metal layer maintains electrical conductivity and ensures uniform current distribution, thereby preserving brightness uniformity. This approach achieves high transmittance through material selection rather than structural discontinuities.
Solution Approach 2:
The patent optimizes the thickness parameters of both the transparent oxide layer and the metal layer to achieve the desired balance between transmittance and conductivity. By carefully controlling the thickness of each layer within specific ranges, the electrode achieves high transmittance without needing holes, while maintaining sufficient conductivity. This parameter optimization resolves the contradiction by finding the optimal thickness values that satisfy both requirements simultaneously.
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 achieves high transparency and conductivity, significantly increasing transmittance while maintaining luminous efficiency, as demonstrated by experimental examples showing improved resistivity and transmittance values compared to conventional methods.
Implementation Method 1
a metal doping of different work functions (such as Mg:Ag) on the organic layer is used as the electron injection layer of a conventional transparent electrode
Implementation Method 2
a material of the injection layer is a metal-doped alkali metal salt or a metal-doped metal oxide
Data Source
AI summary
A light emitting device and a transparent electrode thereof are provided in which the transparent electrode includes a transparent conducting layer and an injection layer. The injection layer is disposed between the transparent conducting layer and a light emitting layer of the light emitting device, wherein a material of the injection layer is a metal-doped alkali metal salt or a metal-doped metal oxide.