Multijunction Solar Cell Mirror Layout for Heat and Spectral Absorption
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Solution Overview
Problem
Current multiple solar cells face challenges in achieving high absorption of solar radiation across a wide spectral range while minimizing heating and production costs, particularly in extraterrestrial systems where radiation defects lead to efficiency losses and cooling is difficult due to the lack of convection.
Innovation Solution
A multiple solar cell design featuring at least two partial cells with different bandgaps, an intermediate layer, and an optical element with a lower mirror element that reflects low-energy radiation back, reducing parasitic absorption and heating, and using a separating layer to minimize the influence of low-energy radiation, along with a thin lower partial cell to reduce defect formation and production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If large layer thicknesses are used to ensure complete absorption in a specific spectral range, then absorption efficiency is improved, but production costs increase due to the need for high-quality epitaxial methods
Solution Approach 1:
The solar cell is divided into multiple partial cells with different bandgaps, each optimized for specific spectral ranges. This segmentation allows thinner layers to achieve complete absorption in their respective ranges, reducing the need for expensive thick epitaxial layers while maintaining high absorption efficiency across the full spectrum.
Solution Approach 2:
Different partial cells are assigned different bandgap properties matched to specific spectral ranges. The upper partial cell has a larger bandgap for high-energy photons, while the lower partial cell has a smaller bandgap for lower-energy photons. This local optimization of material properties enables efficient absorption with reduced layer thicknesses.
2Power
If cooling systems are added to reduce operating temperature and maintain efficiency, then power output is improved, but device complexity increases
Solution Approach 1:
The harmful thermal energy that would otherwise require active cooling is extracted and redirected through the optical element. Low-energy radiation that passes through the partial cells is reflected back by the optical element, creating a passive thermal management system that reduces operating temperature without adding complex cooling machinery.
Solution Approach 2:
The optical element acts as an intermediary between the partial cells and the external environment. It not only manages light absorption but also serves as a thermal management interface, reflecting harmful radiation and reducing heat buildup, thereby maintaining efficiency without requiring separate cooling systems.
3Reliability
If thin partial cells are used to reduce defect formation from radiation, then radiation hardness is improved, but absorption efficiency decreases due to incomplete absorption
Solution Approach 1:
The solar cell structure is segmented into multiple thin partial cells, each optimized for specific spectral ranges. This segmentation allows each layer to be thin enough to maintain radiation hardness while the collective structure achieves complete absorption across all relevant wavelengths through the combination of different bandgaps.
Solution Approach 2:
The solar cell uses a composite structure of multiple semiconductor materials with different bandgaps. This composite approach enables thin layers of each material to collectively provide both radiation resistance and complete spectral absorption, as each material contributes to absorbing specific portions of the spectrum.
4Reliability
If a multiple solar cell with at least three pn junctions is formed to reduce the influence of defects produced by radiation, then radiation hardness is improved, but heating of the multiple solar cell cannot be prevented
Solution Approach 1:
The optical element converts harmful radiation that would cause heating into a beneficial effect. By reflecting low-energy radiation back through the structure, it creates a passive cooling effect that reduces operating temperature, transforming the previously harmful thermal energy into a useful thermal management mechanism.
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 design enhances spectral absorption and reduces heating, maintaining high efficiency while lowering production costs and radiation-induced defects, allowing for effective cooling and improved performance in various applications, including extraterrestrial systems.
Implementation Method 1
an optical element comprising a lower mirror element is arranged on a side of the intermediate layer facing away from the light
Implementation Method 2
the largest possible spectral range of a relevant spectrum, for example of solar radiation, is introduced into the multiple solar cell and correspondingly absorbed in the partial cells
Implementation Method 3
at least one partial cell being formed from a direct semiconductor
Data Source
AI summary
A multiple solar cell having at least two partial cells, at least being formed from a direct semiconductor, having an upper partial cell facing the light and a lower partial cell facing away from the light, an upper bandgap of the upper partial cell being greater than a lower bandgap of the lower partial cell, and an intermediate layer arranged on the lower partial cell side facing away from the light. An optical element including a lower mirror element is arranged on the intermediate layer side facing away from the light, and has a partial element having structural elements arranged in a lateral direction on the intermediate layer side facing away from the light. The structural elements have a mean spacing less than or equal to 1.3 times a spacing value that results from a ratio of a wavelength of the lower bandgap to a refractive index of the lower partial cell or the lower mirror element has a roughness having a root-mean-square value of less than 50 nm.