Inverted Metamorphic Solar Cell with DBR Layer
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Solution Overview
Problem
Current methods for manufacturing inverted metamorphic multijunction solar cells using III-V compound semiconductor materials face challenges in producing commercially viable devices due to difficulties in material selection and fabrication processes, particularly in achieving lattice mismatch and radiation hardness.
Innovation Solution
The development of a multijunction solar cell structure comprising an upper first solar subcell, a middle second solar subcell with a graded interlayer, and a third solar subcell, along with a distributed Bragg reflector layer, which allows for lattice mismatch and improved radiation hardness through specific band gap energies and semiconductor layer configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional manufacturing methods are used for inverted metamorphic multijunction solar cells, then the fabrication process is simpler, but the radiation hardness and manufacturing viability are insufficient
Solution Approach 1:
The solar cell is divided into multiple subcells with different band gap energies arranged in series, where each subcell is optimized for specific wavelength ranges. This segmentation allows each layer to be independently optimized for radiation hardness while maintaining overall manufacturability through modular fabrication processes.
Solution Approach 2:
The patent employs metamorphic grading layers that gradually change material composition and lattice constant parameters between subcells with different band gaps. This parameter transition enables lattice mismatch accommodation and dislocation control, achieving radiation hardness without requiring completely new fabrication methods.
2Use of energy by moving object
If multiple subcells with different band gap energies are used to achieve spectral splitting, then energy conversion efficiency increases, but device complexity increases
Solution Approach 1:
The photovoltaic device is segmented into multiple subcells, each with a specific band gap energy tailored to absorb particular portions of the solar spectrum. This segmentation enables spectral splitting and cumulative current generation, achieving high energy conversion efficiency (exceeding 27% under AM0 illumination) while organizing complexity into manageable functional units.
Solution Approach 2:
The patent uses composite semiconductor structures combining different III-V compound materials with varying band gap energies in a vertically stacked configuration. This composite approach enables simultaneous optimization for different wavelength ranges while maintaining a unified device architecture that manages structural complexity.
3Use of energy by moving object
If III-V compound semiconductor materials are used to achieve higher efficiency, then energy conversion efficiency exceeds silicon technology, but manufacturing complexity and cost increase
Solution Approach 1:
The patent utilizes metamorphic grading techniques that gradually transition material composition parameters between layers with different lattice constants. This parameter change approach enables the integration of high-efficiency III-V compound materials while controlling dislocation densities and maintaining compatibility with existing semiconductor fabrication processes, thereby reducing manufacturing complexity.
Solution Approach 2:
The patent employs an inverted metamorphic structure where the grading layers are positioned opposite to conventional configurations, with the metamorphic buffer located at the bottom rather than top of the stack. This inversion simplifies the fabrication sequence and material deposition processes while achieving the same lattice mismatch management, reducing manufacturing complexity.
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 enhances the efficiency and radiation hardness of solar cells, increasing the short circuit current and overall energy conversion efficiency while reducing the complexity of the manufacturing process.
Implementation Method 1
a distributed Bragg reflector (DBR) layer adjacent to the upper first subcell
Implementation Method 2
upper first solar subcell having a first band gap; a middle second solar subcell adjacent to the first solar subcell and having a second band gap smaller than the first band gap
Data Source
AI summary
A multijunction solar cell comprising an upper first solar subcell having a first band gap; a middle second solar subcell adjacent to the first solar subcell and having a second band gap smaller than the first band gap; a graded interlayer adjacent to the second solar subcell; the graded interlayer having a third band gap greater than the second band gap; a third solar subcell adjacent to the interlayer, the third subcell having a fourth band gap smaller than the second band gap such that the third subcell is lattice mismatched with respect to the second subcell; and a distributed Bragg reflector (DBR) layer adjacent to the upper first subcell.