Multijunction Solar Cells With Light Scattering Layer
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Solution Overview
Problem
The design and manufacturing of space-qualified III-V compound semiconductor multijunction solar cells face challenges in achieving high energy conversion efficiency and radiation resistance while maintaining a favorable power-to-weight ratio, due to complex interdependencies between material parameters such as band gap, doping levels, and crystal lattice matching, which are further complicated by the harsh space environment and rigorous testing protocols.
Innovation Solution
Incorporating a light scattering layer above at least one solar subcell to redirect incoming light along longer path lengths, increasing the probability of absorption, and using a crystallizing layer over a special purpose layer, along with a method of forming a light scattering layer in a multijunction solar cell to enhance energy conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a light scattering layer is added above solar subcells, then light absorption probability increases, but device complexity increases
Solution Approach 1:
A light scattering layer is introduced as an intermediary component between the incoming light and the solar subcells. This layer scatters the light to increase its path length within the subcells, thereby improving absorption probability and energy conversion efficiency without fundamentally changing the subcell structure itself.
Solution Approach 2:
The solar cell structure is enhanced by incorporating composite material layers, specifically the light scattering layer composed of scattering centers embedded in a matrix material. This composite structure enables improved light absorption while maintaining structural integrity and manageable complexity through established material science principles.
2Productivity
If multiple subcells with different band gaps are stacked, then spectral splitting efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The solar cell is divided into multiple subcells, each with a specific band gap optimized for different spectral regions. This segmentation allows spectral splitting where each subcell handles a specific portion of the solar spectrum, maximizing overall energy conversion efficiency while enabling modular manufacturing approaches.
Solution Approach 2:
Each subcell is designed with locally optimized properties, including specific band gap energies and thicknesses tailored to absorb particular wavelength ranges. The light scattering layer also provides localized light trapping enhancement at each subcell interface, ensuring optimal absorption conditions for each segment of the stacked structure.
3Reliability
If lattice matched structures are used, then radiation resistance improves, but adaptability to different spectral conditions decreases
Solution Approach 1:
The patent employs composite material structures where lattice-matched semiconductor layers are combined with a light scattering layer. The lattice-matched subcells provide radiation resistance and structural stability, while the light scattering layer enhances spectral absorption across different conditions, achieving a balance between reliability and adaptability.
Solution Approach 2:
The design utilizes controlled variations in material parameters, such as band gap energies and layer thicknesses, within the lattice-matched structure. By adjusting these parameters while maintaining lattice matching, the cell can be adapted to different spectral conditions (AM0 for space, AM1.5 for terrestrial) without sacrificing radiation resistance.
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 proposed solution improves the energy conversion efficiency of multijunction solar cells by optimizing light absorption and reducing the impact of radiation, thereby enhancing the power output and longevity of solar cells in space missions.
Implementation Method 1
a first light scattering layer arranged above only one of the solar subcells so as to scatter the incoming light into the one solar subcell
Implementation Method 2
Each subcell is designed to convert photons over different spectral or wavelength bands to electrical current
Data Source
AI summary
A multijunction solar cell including an upper first solar subcell having a first band gap and positioned for receiving an incoming light beam; a second solar subcell disposed directly below and adjacent to the upper first solar subcell, and having a second band gap smaller than said first band gap; wherein a light scattering layer is provided below the upper first solar subcell and adjacent to the upper first solar subcell for redirecting the incoming light to be scattered along longer path lengths into the second solar subcell.