III-V Multi-Junction Solar Cell Contacts With Dielectric-Passivated Opening
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Solution Overview
Problem
Existing III-V multi-junction solar cells face challenges in reliable electrical contacting, particularly in extraterrestrial applications, where conventional contact materials like gold and silver are not suitable, and the substrate thinning process can lead to passivation and metallization issues.
Innovation Solution
A stacked III-V multi-junction solar cell design featuring a substrate layer with alternating solar cells of different band gaps, a tunnel diode, and a metallic top contact area with titanium or nickel compounds, along with a dielectric layer and additional metallic layers to ensure reliable and durable electrical connections, avoiding gold and silver compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gold or silver is used for metallic layers in solar cells, then electrical conductivity and reliability are improved, but cost increases and material availability becomes problematic for extraterrestrial applications
Solution Approach 1:
The patent replaces expensive and space-constrained gold/silver with abundant, inexpensive earth metals like titanium and nickel. These alternative metals achieve sufficient electrical conductivity and bonding reliability without the material availability constraints of precious metals in extraterrestrial environments.
Solution Approach 2:
The patent changes the material composition parameters of the metallic layers from precious metals to base metals, adjusting the chemical and physical properties to maintain functional performance while eliminating dependency on scarce resources. Multiple metal layers with different compositions are used to optimize both electrical properties and bonding characteristics.
2Reliability
If multiple metallic layers are applied to ensure durable electrical connections, then bonding reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the metallic coating into multiple functional layers, each serving a specific purpose: adhesion promotion, electrical conductivity, and protection. This segmentation allows each layer to be optimized independently while simplifying the overall manufacturing process compared to using a single complex material system.
Solution Approach 2:
The patent employs composite metallic structures combining different metals (e.g., titanium-nickel combinations) to achieve synergistic effects. The composite approach provides both strong bonding and reliable electrical contact while maintaining manufacturability through established deposition techniques.
3Reliability
If dielectric layers are applied to cover opening side walls and edge areas, then passivation and material-tight bonding are improved, but manufacturing steps increase
Solution Approach 1:
The dielectric layer serves as an intermediary between the metallic layers and the semiconductor substrate, providing essential passivation and ensuring material-tight bonding. This intermediate layer prevents direct interaction between incompatible materials while enabling reliable electrical contact, justifying the additional manufacturing step.
Solution Approach 2:
The dielectric layer is applied in advance before final metallic layer deposition, preparing the surface for subsequent metal coating. This preliminary passivation step prevents contamination and ensures proper adhesion, simplifying later processing steps even though it adds an initial manufacturing step.
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 enhances the reliability of electrical connections, improves passivation, and prevents chipping or cracking, allowing for efficient and durable operation of III-V multi-junction solar cells, especially in extraterrestrial environments.
Implementation Method 1
The side wall and the two edge areas can be completely covered with a dielectric layer
Implementation Method 2
In order to connect the substrate electrically, a flat metallic bottom contact area can be provided on the bottom of the multi-junction solar cell
Implementation Method 3
A tunnel diode can be formed between the first solar cell and the second solar cell
Implementation Method 4
stacked III-V multi-junction solar cell with a top and a bottom
Data Source
AI summary
A stacked III-V multi-junction solar cell with a top and a bottom. A metallic top contact area is formed at the top and has a first layer of metal, a flat metallic bottom contact area formed on the bottom. An opening extends continuously from the top to the bottom and has an upper edge area formed at the top and a lower edge area formed at the bottom. The upper edge area is adjacent to the top contact area and the side wall and the two edge areas are covered with a dielectric layer. The dielectric layer has a top and a bottom. A first metallic top layer is formed on a surface of the first metal layer and on the top of the dielectric layer and a second metallic top layer is formed on a part of the first metal layer adjacent to the upper edge area.