Solar Cell Back Surface Isolation via Varying Doping
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Solution Overview
Problem
Conventional solar cell manufacturing methods lead to reliability issues due to physical contact between conductive type regions, resulting in short-circuits and reduced productivity, as they require additional processes and area reduction on the semiconductor substrate.
Innovation Solution
A solar cell design with a semiconductor substrate featuring a first and second conductive type region, where the second region is spaced from the edge and has a varying doping concentration or junction depth along its boundary, allowing for an isolation portion to be formed without additional processes, preventing reverse current and maximizing the effective area for photoelectric transformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive type regions are formed separately with isolation portions, then reliability is improved, but productivity deteriorates due to additional manufacturing processes
Solution Approach 1:
The patent combines the formation of the isolation portion and the back electric field region into a single ion implantation process. By using a mask during ion implantation, the isolation portion is formed simultaneously with the back electric field region, eliminating the need for separate manufacturing steps and improving productivity while maintaining reliability.
Solution Approach 2:
The mask is placed on the semiconductor substrate before ion implantation to predefine the regions where dopants will be implanted. This preliminary action allows the isolation portion and back electric field region to be formed in the correct positions simultaneously, preventing short-circuits while streamlining the manufacturing process.
2Reliability
If isolation portion is formed on front surface, then reliability is improved, but effective area is reduced resulting in efficiency deterioration
Solution Approach 1:
The patent moves the isolation portion from the front surface to the back surface of the semiconductor substrate. By forming the isolation portion on the back surface along with the back electric field region, the front surface is preserved for maximum photoelectric conversion area, eliminating the trade-off between reliability and efficiency.
3Reliability
If conductive type regions are spaced from edge, then short-circuit is prevented, but manufacturing complexity increases
Solution Approach 1:
The isolation portion and back electric field region are formed in a single ion implantation step using a mask, simplifying the manufacturing process. The mask automatically defines the spacing from the edge, preventing short-circuits without requiring complex multi-step manufacturing procedures.
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 the reliability and productivity of solar cells by preventing unnecessary short-circuits and improving photoelectric conversion efficiency while maintaining high manufacturing efficiency.
Implementation Method 1
forming a conductive type region includes ion-implanting a dopant while placing a mask covering at least an edge of the semiconductor substrate on the semiconductor substrate
Implementation Method 2
solar cells which convert solar energy into electrical energy
Data Source
AI summary
Discussed is a solar cell including a semiconductor substrate, a first conductive type region formed on a surface of the semiconductor substrate, a second conductive type region formed on the other surface of the semiconductor substrate, the second conductive type region being spaced from an edge of the semiconductor substrate and having a conductive type different from that of the first conductive type region, an isolation portion formed at a perimeter of the second conductive type region on the other surface of the semiconductor substrate, a first electrode connected to the first conductive type region, and a second electrode connected to the second conductive type region, wherein the second conductive type region has a boundary portion in a part adjacent to the isolation portion, and in which a doping concentration or a junction depth varies over a width of the boundary portion.