Inverted Metamorphic Multijunction Solar Cell Joining Method
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Solution Overview
Problem
Existing methods for manufacturing inverted metamorphic multijunction solar cells using III-V compound semiconductor materials face challenges in achieving commercially viable and energy-efficient production due to difficulties in material selection and fabrication steps.
Innovation Solution
A method involving the sequential growth of semiconductor subcells with varying band gaps and lattice constants, using a graded interlayer and mechanical bonding, where high band gap subcells are grown epitaxially on a substrate and lower band gap subcells are lattice-mismatched, with a surrogate substrate supporting the structure, allowing for efficient radiation absorption and current collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional manufacturing methods are used for inverted metamorphic multijunction solar cells, then the process is simpler, but energy conversion efficiency and radiation resistance are insufficient
Solution Approach 1:
The solar cell is divided into multiple junctions (typically three or more) with progressively narrower bandgaps, where each junction is optimized for specific portions of the solar spectrum. This segmentation allows the device to capture different wavelengths of light efficiently while maintaining radiation resistance through the distributed structure.
Solution Approach 2:
The bandgap parameter is systematically varied across different junctions, creating a gradient from wider to narrower bandgaps. This parameter change enables optimal spectral splitting and energy capture, improving both efficiency and radiation resistance by matching the solar spectrum distribution.
2Power
If III-V compound semiconductor materials are used to achieve high energy conversion efficiency, then power-to-weight ratio improves, but manufacturing complexity and cost increase
Solution Approach 1:
The heavy metal substrates traditionally required for III-V compound growth are removed or replaced with lightweight surrogate substrates. This extraction of the heavy substrate component maintains the high efficiency benefits of III-V materials while dramatically reducing the overall device weight and simplifying manufacturing.
Solution Approach 2:
The solar cell employs composite structures combining different III-V compound semiconductor materials with varying bandgaps (e.g., GaInP, GaAs, Ge) in a multijunction configuration. This composite approach enables optimization of each layer for specific spectral regions, achieving high power-to-weight ratio through efficient light capture across the solar spectrum.
3Loss of energy
If multiple photovoltaic regions with different band gap energies are used for spectral splitting, then energy conversion efficiency increases, but device structure becomes more complex
Solution Approach 1:
Multiple photovoltaic regions with different bandgaps are merged into a single integrated multijunction device structure. This combining of separate functional regions into one unified device achieves spectral splitting and high energy conversion efficiency without the complexity of assembling multiple separate components, as the current paths are naturally integrated through the series-connected junctions.
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 approach enables the production of high-efficiency multijunction solar cells with improved radiation resistance and power-to-weight ratio, enhancing energy conversion efficiency and reducing manufacturing complexities.
Implementation Method 1
a graded interlayer positioned between the first subcell and the second subcell, where the graded interlayer has a lattice constant that changes gradually from the lattice constant of the first subcell to the lattice constant of the second subcell
Implementation Method 2
III-V compound semiconductor multijunction devices have greater energy conversion efficiencies and generally more radiation resistance
Data Source
AI summary
A method of manufacturing a solar cell by providing a first semiconductor substrate and depositing a first sequence of layers of semiconductor material to form a first solar subcell, including a first bond layer disposed on the top of the first sequence of layers. A second semiconductor substrate is provided, and on the top surface of the second substrate a second sequence of layers of semiconductor material is deposited forming at least a second solar subcell. A second bond layer is disposed on the top of said second sequence of layers. The first solar subcell is mounted on top of the second solar subcell by joining the first bond layer to the second bond layer in an ultra high vacuum chamber, and the first semiconductor substrate is removed.