Transparent Cathode Stack for Low-Resistance Display Electrodes
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Solution Overview
Problem
Display devices face issues with high sheet resistance and defects in the cathode electrode due to its high sheet resistance, which affects light transmittance and functionality.
Innovation Solution
A multi-layered electrode structure is employed, comprising a first electrode layer of titanium or tantalum, a second electrode layer of silver or silver alloy, and a third electrode layer of indium zinc oxide, with specific thicknesses and etching to ensure low sheet resistance and high light transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the cathode electrode is formed as a single layer structure of metal to ensure light transmittance, then light transmittance is improved, but sheet resistance becomes high causing defects
Solution Approach 1:
The cathode electrode is constructed as a composite multi-layer structure comprising a first electrode layer (titanium or tantalum, 30-50 Å thick), a second electrode layer (silver or silver alloy, 42-58 Å thick), and a third electrode layer (transparent conductive material like IZO, 1000-3000 Å thick). This composite structure combines the advantages of each material: the first layer provides ohmic contact, the second layer provides low sheet resistance, and the third layer provides high light transmittance, thereby resolving the contradiction between light transmittance and defect reduction.
Solution Approach 2:
The cathode electrode is segmented into three distinct functional layers, each performing a specific function. The segmentation allows optimization of each layer's thickness and material properties independently, enabling the overall electrode to achieve both high light transmittance and low sheet resistance without defects.
2Device complexity
If the cathode electrode is formed as a single layer structure of metal, then device complexity is reduced, but sheet resistance becomes high causing voltage drop
Solution Approach 1:
The multi-layer composite electrode structure with titanium/tantalum (30-50 Å), silver/silver alloy (42-58 Å), and transparent conductive material (1000-3000 Å) provides progressively lower sheet resistance at each layer, reducing voltage drop and energy loss while maintaining manageable structural complexity through systematic material selection and thickness control.
Data Source
AI summary
A display device includes: a first electrode; a semiconductor stacked member including a first semiconductor layer, a second semiconductor layer, and an active layer between the first semiconductor layer and the second semiconductor layer, and located on the first electrode; and a second electrode on the semiconductor stacked member, the second electrode including: a first electrode layer on the semiconductor stacked member; a second electrode layer on the first electrode layer, the second electrode layer having a lower sheet resistance than the first electrode layer; and a third electrode layer on the second electrode layer, the third electrode layer including a transparent conductive material.