Light-Emitting Element With Intermediate Layer for Low Resistivity
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Solution Overview
Problem
Current light-emitting elements in display devices face challenges in achieving improved electrical characteristics and transparency, particularly in reducing contact resistivity and enhancing light extraction efficiency.
Innovation Solution
The light-emitting element design includes a first semiconductor layer doped with an n-type dopant, a second semiconductor layer doped with a p-type dopant, a light-emitting layer between them, a first intermediate layer with a metal, and an electrode layer, where the first intermediate layer facilitates ohmic contact and allows light transmission, with specific materials and thicknesses optimized for high transmittance and low contact resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional electrode layer is used directly on the semiconductor layer, then electrical contact is established, but contact resistivity is high and light transmittance is reduced
Solution Approach 1:
The electrode structure is divided into multiple functional layers: a first electrode layer for electrical contact, a first intermediate layer for ohmic contact enhancement, and a second electrode layer for light extraction. This segmentation allows each layer to optimize its specific function without compromising the others, achieving both low contact resistivity and high light transmittance
Solution Approach 2:
The first intermediate layer acts as a mediator between the semiconductor layer and the electrode layers. It facilitates ohmic contact formation, reducing contact resistivity while maintaining optical transparency. The intermediate layer includes materials such as indium tin oxide (ITO), indium zinc oxide (IZO), or aluminum zinc oxide (AlZO) that provide both electrical and optical functionality
2Reliability
If the intermediate layer is made thicker to improve ohmic contact, then contact resistivity decreases, but light transmittance is reduced
Solution Approach 1:
The thickness of the first intermediate layer is precisely controlled within the range of 50-200 nm. This parameter optimization ensures sufficient material presence for ohmic contact formation while maintaining adequate optical transparency. The specific thickness range balances electrical and optical requirements without requiring trial-and-error adjustments
Solution Approach 2:
The first intermediate layer uses composite material compositions such as indium tin oxide (ITO), indium zinc oxide (IZO), or aluminum zinc oxide (AlZO). These composite oxide materials provide synergistic properties combining high electrical conductivity for low contact resistivity with high optical transparency for maintaining light transmittance
3Illumination intensity
If transparent conductive materials are used for the electrode layer, then light transmittance is improved, but electrical conductivity is reduced
Solution Approach 1:
The electrode system is segmented into multiple layers with different functional priorities: the first electrode layer prioritizes electrical conductivity for low contact resistivity, while the second electrode layer prioritizes optical transparency for high light extraction. This segmentation resolves the trade-off by distributing electrical and optical functions across separate layers
Solution Approach 2:
The first intermediate layer serves dual functions simultaneously: it provides ohmic contact for electrical conduction while maintaining optical transparency for light transmission. This multi-functionality eliminates the need for separate specialized layers, streamlining the device structure while achieving both electrical and optical performance goals
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 reduces contact resistivity to ≤10−3 Ωcm2 and achieves light transmittance of ≥70%, ensuring uniform driving current and improved light extraction efficiency.
Implementation Method 1
the first intermediate layer facilitates ohmic contact and allows light transmission
Implementation Method 2
light from the light-emitting layer transmits through the first semiconductor layer, the first intermediate layer, and the electrode layer at a transmittance equal to or greater than about 70%
Data Source
AI summary
A light-emitting element and a display device including the same are provided. The light-emitting element comprises a first semiconductor layer doped with an n-type dopant, a second semiconductor layer disposed below the first semiconductor layer and doped with a p-type dopant, a light-emitting layer disposed between the first semiconductor layer and the second semiconductor layer, a first intermediate layer disposed on the first semiconductor layer, and including a metal, and an electrode layer disposed on the first intermediate layer. Light from the light-emitting layer transmits through the first semiconductor layer, the first intermediate layer, and the electrode layer at a transmittance equal to or greater than about 70%.