Polycrystalline Silicon Contacts with ARC Surface-Recombination Control
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Solution Overview
Problem
Conventional high-temperature firing of conductive paste in polycrystalline silicon solar cells leads to high surface recombination, limiting efficiency gains.
Innovation Solution
A fabrication process involving high-temperature firing of conductive paste followed by a low-temperature anneal after anti-reflective coating deposition, which forms metal lines beneath the ARC layer, maintaining low surface recombination and enabling efficient conductive contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature firing of conductive paste is performed, then conductive contact formation is improved, but surface recombination increases
Solution Approach 1:
The patent applies preliminary action by forming the anti-reflective coating layer before the high-temperature firing process. This pre-formed layer acts as a protective barrier that will withstand the subsequent high-temperature treatment, allowing the conductive paste to be fired at high temperatures to form reliable conductive contacts while the pre-existing ARC layer prevents excessive surface recombination from occurring during the firing process.
2Reliability
If high-temperature firing is used to form conductive contacts, then contact conductivity is improved, but solar cell efficiency deteriorates due to surface recombination
Solution Approach 1:
The patent converts the potentially harmful high-temperature firing process into a beneficial outcome by having the anti-reflective coating layer already in place before firing. The ARC layer, which is normally designed to reduce reflection and improve light absorption, is repurposed here as a thermal and chemical barrier during the firing process, enabling high-temperature processing that forms excellent conductive contacts while the layer itself protects against the harmful effects that would otherwise reduce solar cell efficiency.
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
The process allows for high-temperature firing while minimizing surface recombination, enhancing the efficiency and cost-effectiveness of polycrystalline silicon solar cells.
Implementation Method 1
firing the conductive paste at a temperature above approximately 700 degrees Celsius to form a conductive contact
Implementation Method 2
forming an anti-reflective coating (ARC) layer on the polycrystalline silicon feature and the conductive contact
Implementation Method 3
a low-temperature anneal after anti-reflective coating deposition
Data Source
AI summary
Methods of fabricating conductive contacts for polycrystalline silicon features of solar cells, and the resulting solar cells, are described. In an example, a method of fabricating a solar cell includes providing a substrate having a polycrystalline silicon feature. The method also includes forming a conductive paste directly on the polycrystalline silicon feature. The method also includes firing the conductive paste at a temperature above approximately 700 degrees Celsius to form a conductive contact for the polycrystalline silicon feature. The method also includes, subsequent to firing the conductive paste, forming an anti-reflective coating (ARC) layer on the polycrystalline silicon feature and the conductive contact. The method also includes forming a conductive structure in an opening through the ARC layer and electrically contacting the conductive contact.