Inverted Metamorphic Solar Cell Via Backside Contacts
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Solution Overview
Problem
Current solar cell designs for sophisticated applications like satellites face limitations in power and energy conversion efficiency due to the placement of anode and cathode terminals, which are typically on opposite sides of the cell, affecting reliability and cost, and there is a lack of designs with both contacts on the same side.
Innovation Solution
A multijunction solar cell structure with a via and electrical conductor extending through it, allowing both anode and cathode terminals to be placed on the back side, featuring a grading interlayer and lattice-mismatched subcells with specific band gaps, along with insulated contact pads and metal layers for efficient energy conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both anode and cathode terminals are placed on opposite sides of the solar cell, then internal interconnections are avoided, but the device complexity and cost increase, and reliability decreases
Solution Approach 1:
The patent places both anode and cathode terminals on the same side (back side) of the solar cell by using a via structure that extends through the cell thickness. This dimensional reconfiguration allows terminals to be accessed from a single plane, eliminating the need for backside routing and reducing device complexity while improving reliability through shorter interconnection paths.
2Device complexity
If both anode and cathode terminals are placed on the same side of the solar cell, then device complexity and cost are reduced, but internal interconnections are required
Solution Approach 1:
The patent implements a nested structure where the via extends through the solar cell thickness and contains electrical conductors within it. The via structure nests the conductor, contact pad, and interconnection elements in a compact vertical arrangement, allowing both terminals to be accessed from the back side while maintaining reliable electrical connections through the cell structure.
3Productivity
If conventional terminal placement is used, then manufacturing is simpler, but power and energy conversion efficiency are limited for sophisticated applications
Solution Approach 1:
The patent segments the solar cell structure into distinct functional layers including the via structure, contact pads, and interconnection elements. This segmentation allows for optimized electrical pathways and terminal configuration that improve power and energy conversion efficiency, while the modular via structure maintains ease of manufacture through standardized fabrication processes.
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 configuration enhances energy conversion efficiency and reduces the size and mass of satellite power systems by enabling both terminals to be on the same side, improving reliability and cost-effectiveness for advanced applications.
Implementation Method 1
Photovoltaic cells, also called solar cells, are one of the most important new energy sources that have become available in the past several years
Implementation Method 2
a grading interlayer disposed over the second subcell and having a third band gap greater than the second band gap; and a third solar subcell adjacent the back side surface and disposed over the interlayer, the third subcell being lattice mis-matched with respect to said second subcell
Data Source
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AI summary
A method of forming a multijunction solar cell including an upper subcell, a middle subcell, and a lower subcell by providing a first substrate for the epitaxial growth of semiconductor material; forming a first solar subcell on the substrate having a first band gap; forming a second solar subcell over the first subcell having a second band gap smaller than the first band gap; forming a grading interlayer over the second subcell having a third band gap larger than the second band gap; forming a third solar subcell having a fourth band gap smaller than the second band gap such that the third subcell is lattice mis-matched with respect to the second subcell; and etching a via from the top of the third subcell to the substrate to enable both anode and cathode contacts to be placed on the backside of the solar cell.