Solar Cell Metallization with Dual-Structure Contact
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Solution Overview
Problem
Conventional silicon solar cells face challenges in achieving high adhesion between the semiconductor wafer, dielectric layer, and metal layer, particularly when aiming for full-surface aluminum paste metallization without silver paste areas, which are costly and reduce efficiency.
Innovation Solution
A solar cell production method involving a contact structure with a combination of first and second structures of different dimensions within the dielectric layer, where the minimum dimension of the first structure is larger than the maximum dimension of the second structure, providing point contact points for enhanced adhesion, and using aluminum-silicon eutectic and laser-induced contacts to improve adhesion between the metal and semiconductor wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver paste areas are used on the back of solar cells for soldering connections, then adhesion between metal layer and silicon wafer is achieved through silver paste penetrating the dielectric layer, but production costs increase and solar cell efficiency decreases
Solution Approach 1:
The invention extracts and eliminates the silver paste component from the metallization structure by implementing a dual-structure aluminum paste system. The first structure (large-area) and second structure (small-area/point contact) work together to provide both adhesion and electrical connection functions previously requiring silver paste, thereby removing the costly and efficiency-reducing silver paste areas while maintaining reliable adhesion through the aluminum paste structures penetrating the dielectric layer
Solution Approach 2:
The invention creates a composite metallization system combining two different aluminum paste formulations with distinct functional properties. The first structure uses aluminum paste optimized for large-area coverage and adhesion, while the second structure uses aluminum paste formulated for point contact penetration and electrical conductivity. This composite approach replaces the traditional silver-aluminum metallization system, achieving both cost reduction and efficiency improvement while maintaining reliable adhesion
2Ease of manufacture
If full-surface aluminum paste metallization is implemented on the back of solar cells to reduce costs, then production costs decrease, but adhesion between metal layer and silicon wafer becomes insufficient without silver paste penetration
Solution Approach 1:
The invention segments the aluminum paste metallization into two distinct functional structures: the first structure (large-area) providing broad coverage and mechanical support, and the second structure (small-area/point contact) providing localized penetration through the dielectric layer to establish strong adhesion bonds with the silicon wafer. This segmentation allows each structure to be optimized for its specific function, with the second structure's point contacts delivering the adhesion performance previously achieved only by silver paste penetration
Solution Approach 2:
The invention applies local quality by concentrating the adhesion-critical penetration function in the second structure's small-area point contacts, while the first structure provides general coverage. The second structure's aluminum paste is specifically formulated and positioned to penetrate the dielectric layer at critical locations, creating localized high-strength adhesion zones that collectively provide sufficient overall adhesion without requiring full-surface silver paste
3Productivity
If a dielectric passivation layer is inserted between the rear-side metallization and silicon surface to increase efficiency, then solar cell efficiency increases, but adhesion between metal layer and silicon wafer becomes difficult to achieve
Solution Approach 1:
The invention uses the second structure's small-area point contact aluminum paste as an intermediary mechanism that bridges the dielectric passivation layer and the silicon wafer. The point contact structure is specifically designed to penetrate through the dielectric layer, creating a direct metallurgical bond with the silicon substrate while maintaining the integrity of the dielectric passivation in non-contact areas. This intermediary penetration approach allows the metal layer to adhere to the silicon wafer through the dielectric barrier, preserving both the efficiency benefits of passivation and the adhesion requirements
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 method achieves high adhesive strength between the semiconductor wafer, dielectric layer, and metal layer, enabling direct interconnection while reducing costs by eliminating silver paste and maintaining the efficiency of the solar cell, with the combination of large and small-area adhesion points optimizing the solar cell's performance.
Implementation Method 1
The adhesion is achieved by the aluminum paste penetrating the dielectric layer and thereby producing a sufficiently high adhesion with the silicon wafer
Implementation Method 2
laser-induced contacts to improve adhesion between the metal and semiconductor wafer
Data Source
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AI summary
The present invention relates to a solar cell (1) comprising a semiconductor wafer (3), at least one dielectric layer (5) arranged on the semiconductor wafer (3), a metal layer (7) arranged on the dielectric layer, and a contact structure arranged in the dielectric layer (5) such that the contact structure provides an electrical connection between the metal layer (7) and the semiconductor wafer (3), wherein the contact structure has at least one first structure (9a) having a minimum dimension and at least one second structure (9b) having a maximum dimension, wherein the minimum dimension and the maximum dimension are defined along a surface of the semiconductor wafer (3) and the minimum dimension of the first structure (9a) is greater than the maximum dimension of the second structure (9b). Furthermore, the present invention relates to a solar cell production method, comprising the following method steps: providing a semiconductor wafer (3) with at least one dielectric layer (5), forming a metal layer (7) on the dielectric layer (5) and a contact structure arranged in the dielectric layer (5), such that the contact structure provides an electrical connection between the metal layer (7) and the semiconductor wafer (3), wherein at least one first structure (9a) having a minimum dimension and at least one second structure (9b) having a maximum dimension are formed as contact structure, such that the minimum dimension of the first structure (9a) is greater than the maximum dimension of the second structure (9b).