Back-contact cell isolation grooves for leakage prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Back-contact cells face issues with electric leakage and micro-short-circuiting due to poor insulation between semiconductor layers, which affect conversion efficiency and require excessive silver paste usage.
Innovation Solution
The introduction of isolation grooves disposed above the contact interface between semiconductor layers, combined with a conductive composite layer, enhances insulation and reduces the need for silver paste by acting as a finger electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a thin intrinsic amorphous silicon layer is used for insulation between semiconductor layers, then the device structure is simple, but electric leakage and micro-short-circuiting occur due to poor insulation
Solution Approach 1:
The insulation structure is segmented into multiple functional layers: a thin intrinsic amorphous silicon layer (10 nm) for basic insulation, a tungsten oxide layer (50-200 nm) for enhanced insulation and barrier properties, and a conductive film layer for carrier collection. This segmentation allows each layer to perform its specific function optimally while maintaining overall structural simplicity.
Solution Approach 2:
The patent employs a composite insulation structure combining different materials with complementary properties: intrinsic amorphous silicon provides basic passivation, tungsten oxide provides enhanced insulation and barrier characteristics, and the conductive film layer provides carrier collection. This composite approach achieves superior insulation performance without significantly increasing structural complexity.
2Productivity
If conductive film layer is deposited on the second semiconductor layer, then carriers are collected effectively, but electric leakage increases at the boundary region
Solution Approach 1:
The tungsten oxide layer acts as an intermediary barrier between the conductive film layer and the semiconductor layers. It provides an additional insulation layer that prevents direct contact and reduces electric leakage at the boundary region, while still allowing effective carrier collection through the conductive film layer above it.
Solution Approach 2:
The boundary region uses a composite structure combining tungsten oxide (insulating material) with the conductive film layer. The tungsten oxide provides the necessary insulation to prevent electric leakage, while the conductive film layer maintains carrier collection efficiency, achieving both functions simultaneously.
3Reliability
If better conductivity is achieved in semiconductor layers, then carrier transport improves, but electric leakage phenomenon becomes more serious
Solution Approach 1:
The tungsten oxide layer serves as an intermediary barrier that decouples the conductivity function from the insulation function. It allows the semiconductor layers to achieve high conductivity for carrier transport while the tungsten oxide layer prevents electric leakage by providing an additional insulation barrier.
Solution Approach 2:
The patent uses a composite structure where highly conductive semiconductor layers are combined with the insulating tungsten oxide layer. This composite approach enables the semiconductor layers to achieve optimal conductivity for carrier transport while the tungsten oxide layer prevents electric leakage, resolving the contradiction between conductivity and leakage prevention.
4Reliability
If grid electrodes use excessive silver paste, then electrical connection is ensured, but cost increases significantly
Solution Approach 1:
The patent replaces expensive silver paste with a conductive film layer deposited by physical vapor deposition. This thin film layer provides sufficient electrical connection and carrier collection functionality while using minimal material, dramatically reducing costs compared to traditional silver paste grid electrodes.
Solution Approach 2:
The patent substitutes the mechanical/sputtering-based silver paste application process with a physical vapor deposition process that deposits a thin conductive film layer. This substitution eliminates the need for excessive silver paste while ensuring reliable electrical connection and carrier collection, significantly reducing material costs.
Data Source
Figure 1~3
Figure 3a~3b
Figure 4~5a
AI summary
A back-contact cell with isolation grooves specifically disposed and a preparation method thereof are provided. The back-contact cell includes: a silicon substrate having, on a back side, a polished region and a textured region disposed alternately along an X-axis direction of the back side, a first semiconductor layer disposed on the polished region, and a second semiconductor layer disposed on the textured region. The back-contact cell further includes a conductive film layer and a conductive mask layer sequentially disposed outwardly along a Z-axis direction of the back side. A conductive composite layer formed by the conductive mask layer and the conductive film layer is provided with isolation grooves disposed at intervals along the X-axis direction. The isolation groove is located above a contact interface between the first semiconductor layer and the second semiconductor layer in the Z-axis direction, and the isolation groove spans part of the polished region and part of the textured region in the X-axis direction. (Fig. 5)