Multi-junction Solar Cell with Mesa Trench Protection Diode
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Solution Overview
Problem
Existing solar cell devices with multiple junctions and protective diode structures lack efficient integration and reliability, particularly in terms of semiconductor layer complexity and manufacturing processes.
Innovation Solution
A solar cell device with a multi-junction solar cell and protective diode structure sharing a common back surface, separated by a mesa trench, where the protective diode structure has fewer semiconductor layers than the multi-junction solar cell, with tunnel diodes arranged between adjacent solar cells and diodes, utilizing existing semiconductor and metal layers for contact structures, and employing a sequence of semiconductor layers mirroring the multi-junction solar cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protective diode structure uses the same number of semiconductor layers as the multi-junction solar cell, then the integration is more complete, but the manufacturing complexity and material consumption increase
Solution Approach 1:
The patent extracts only the necessary protective diode structure from the full multi-junction solar cell stack. The protective diode structure contains fewer semiconductor layers than the complete solar cell, removing unnecessary layers while retaining the essential protective function. This reduces manufacturing complexity and material consumption while maintaining integration through shared backend processing.
2Ease of manufacture
If metal contacts are formed directly on the protective structure without additional layers, then the manufacturing process is simplified, but the electrical connection reliability may be compromised
Solution Approach 1:
The patent makes the contact layer structure universal by using the same contact layer sequence for both the multi-junction solar cell and the protective diode structure. The contact layer (including tunnel diode, n-type layer, and p-type layer) serves dual purposes: providing electrical connection for the solar cell and forming reliable contacts for the protective diode. This eliminates the need for additional protective layers specifically for the diode structure.
Solution Approach 2:
The existing contact layer structure of the solar cell serves the additional function of providing reliable electrical connections for the protective diode structure. The tunnel diode and doped layers in the contact structure inherently provide the necessary electrical pathways and protection, making additional protective layers redundant.
3Loss of substance
If the protective diode structure has fewer semiconductor layers, then the material consumption is reduced, but the structural integrity and performance may be affected
Solution Approach 1:
The patent segments the semiconductor structure into two distinct parts: the full multi-junction solar cell stack and the reduced protective diode structure. The protective diode structure contains only the necessary layers (intrinsic layer, n-type layer, p-type layer, and contact layer) while sharing the common back surface and electrical connection structure with the solar cell. This segmentation reduces material consumption while maintaining structural integrity through shared backend components.
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 the reliability and long-term stability of the protective diode structure, simplifies the manufacturing process, and maintains minimal voltage drop even at high current densities, while increasing yield and efficiency by using existing materials for contact formation.
Implementation Method 1
a multi-junction solar cell (MS) and a protection diode structure (SD)... the light passes through the front side enters the multi-junction solar cell
Implementation Method 2
between adjacent solar cells a tunnel diode is arranged... a tunnel diode being arranged between adjacent protective diodes
Data Source
Figure 1
Figure 2
AI summary
Solar cell device comprising a multi-junction solar cell and a protection diode structure, wherein the multi-junction solar cell and the protection diode structure have a common back surface and front surfaces separated by a mesa trench, and the common back surface comprises an electrically conductive layer and light enters the multi-junction solar cell through the front surface, and wherein the multi-junction solar cell comprises a stack of multiple solar cells, and has an upper solar cell closest to the front surface and a lower solar cell closest to the back surface, and each solar cell comprises an np junction and a tunnel diode is arranged between adjacent solar cells, and the number of semiconductor layers in the protection diode structure is less than the number of semiconductor layers in the multi-junction solar cell.However, the sequence of semiconductor layers in the protection diode structure corresponds to the sequence of semiconductor layers in the multi-junction solar cell, wherein the protection diode structure includes at least one upper protection diode and one lower protection diode located closest to the rear side, and a tunnel diode is arranged between adjacent protection diodes, and the number of np junctions in the protection diode structure is at least one less than the number of np junctions in the multi-junction solar cell, and a terminal contact structure comprising one or more metal layers and an electrically conductive contact layer consisting of several semiconductor layers is formed on the front side of the multi-junction solar cell and the protection diode structure, and the contact layer includes a tunnel diode.