Four-Junction Solar Cell Band Gap Layout for Space Radiation Resistance
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Solution Overview
Problem
Existing multijunction solar cells face challenges in achieving high photoconversion efficiency and maintaining efficiency over the operational life of photovoltaic power systems, particularly in space applications, due to factors such as subcell composition, band gap selection, and radiation resistance.
Innovation Solution
A four junction solar cell design with specific band gaps and lattice matching, incorporating a distributed Bragg reflector layer, and optimized semiconductor materials like indium gallium aluminum phosphide, indium gallium arsenide, and germanium, to enhance efficiency and radiation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of subcells is increased to improve spectral splitting and energy conversion efficiency, then photoconversion efficiency is improved, but device complexity increases
Solution Approach 1:
The solar cell is divided into four distinct subcells, each with a specific band gap energy (first subcell: 2.0-2.15 eV, second subcell: 1.65-1.8 eV, third subcell: approximately 1.41 eV, fourth subcell: approximately 0.67 eV). Each subcell is designed to absorb photons in specific wavelength ranges, enabling spectral splitting and improving overall photoconversion efficiency by capturing a broader spectrum of sunlight.
Solution Approach 2:
The patent optimizes the band gap energies of the four subcells to specific ranges (2.0-2.15 eV, 1.65-1.8 eV, 1.41 eV, and 0.67 eV) to maximize spectral coverage. The average band gap is maintained greater than 1.44 eV to balance voltage output and efficiency. These parameter optimizations enable high photoconversion efficiency while managing the complexity of the multijunction structure.
2Productivity
If the average band gap is increased to improve voltage output and efficiency, then energy conversion efficiency is improved, but absorption of lower energy photons is reduced
Solution Approach 1:
The solar cell is divided into four distinct subcells, each with a specific band gap energy (first subcell: 2.0-2.15 eV, second subcell: 1.65-1.8 eV, third subcell: approximately 1.41 eV, fourth subcell: approximately 0.67 eV). Each subcell is designed to absorb photons in specific wavelength ranges, enabling spectral splitting and improving overall photoconversion efficiency by capturing a broader spectrum of sunlight.
Solution Approach 2:
The patent optimizes the band gap energies of the four subcells to specific ranges (2.0-2.15 eV, 1.65-1.8 eV, 1.41 eV, and 0.67 eV) to maximize spectral coverage. The average band gap is maintained greater than 1.44 eV to balance voltage output and efficiency. These parameter optimizations enable high photoconversion efficiency while managing the complexity of the multijunction structure.
3Adaptability or versatility
If semiconductor layers with different crystal lattice constants are used to achieve desired band gaps, then band gap optimization is improved, but manufacturing precision deteriorates due to lattice mismatch
Solution Approach 1:
The patent optimizes the band gap energies of the four subcells to specific ranges (2.0-2.15 eV, 1.65-1.8 eV, 1.41 eV, and 0.67 eV) to maximize spectral coverage. The average band gap is maintained greater than 1.44 eV to balance voltage output and efficiency. These parameter optimizations enable high photoconversion efficiency while managing the complexity of the multijunction structure.
Solution Approach 2:
The patent employs III-V compound semiconductor materials (such as GaInP, GaInAs, and Ge) that can be compositionally tuned to achieve both the desired band gap energies and lattice matching. By using composite semiconductor structures with controlled compositions, the patent simultaneously optimizes optical properties (band gaps) and structural properties (lattice constants) to ensure high manufacturing precision and device performance.
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 design achieves increased efficiency and improved radiation resistance, maintaining high performance over the operational life of the solar cell, even under high temperature and radiation conditions, outperforming traditional cells in both beginning-of-life and end-of-life scenarios.
Implementation Method 1
incorporating a distributed Bragg reflector layer
Implementation Method 2
photons pass through the subcells, the photons in a wavelength band that are not absorbed and converted to electrical energy
Data Source
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AI summary
A four junction solar cell comprising: an upper first solar subcell composed of indium gallium aluminum phosphide and having a first band gap; a second subcell adjacent to said first solar subcell including an emitter layer composed of indium gallium phosphide or aluminum gallium arsenide, and a base layer composed of aluminum gallium arsenide and having a second band gap smaller than the first band gap and being lattice matched with the upper first solar subcell; a third solar subcell adjacent to said second solar subcell and composed of indium gallium arsenide and having a third band gap smaller than the second band gap and being lattice matched with the second solar subcell; and a fourth solar subcell adjacent to said third solar subcell and composed of germanium and having a fourth band gap smaller than the third band gap.