Silicone Oil Organic Vehicle for PERC Solar Cell Paste
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Solution Overview
Problem
There is a need for electroconductive compositions that are highly conductive and have limited chemical reactivity with the underlying surface layers of passivated emitter rear solar cells to improve electrical performance without damaging the rear passivation or capping layers.
Innovation Solution
An electroconductive paste composition comprising conductive metallic particles, lead-free glass frit, and an organic vehicle with at least one silicone oil is used to form backside soldering tabs on PERC solar cells, minimizing etching of the rear surface layers and enhancing electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electroconductive paste is used to form backside soldering tabs, then electrical conductivity is achieved, but chemical reactivity damages the rear passivation and capping layers
Solution Approach 1:
The patent introduces an intermediary organic vehicle comprising silicone oil that acts as a protective medium between the electroconductive paste and the rear passivation/capping layers. This organic vehicle minimizes chemical reactivity while allowing electrical conductivity to pass through, thereby protecting the sensitive surface layers from damage during the paste application and firing process.
Solution Approach 2:
The patent modifies the chemical composition parameters of the organic vehicle by incorporating silicone oil with specific properties (viscosity, chemical inertness). This parameter change reduces the chemical reactivity of the paste formulation, allowing it to maintain electrical conductivity without damaging the rear surface layers of PERC solar cells.
2Reliability
If the electroconductive paste is made more conductive, then electrical performance improves, but chemical reactivity with surface layers increases
Solution Approach 1:
The organic vehicle serves as a mediator that decouples the relationship between conductivity and chemical reactivity. It allows high conductivity to be achieved through metallic particles while the organic matrix itself remains chemically inert toward the surface layers, thus resolving the trade-off between electrical performance and chemical stability.
Solution Approach 2:
The electroconductive paste is formulated as a composite material combining conductive metallic particles with a chemically inert organic vehicle containing silicone oil. This composite structure enables the conductive function to be separated from the chemically reactive components, allowing high conductivity without increased reactivity toward the rear passivation and capping layers.
Data Source
AI summary
The invention relates to a passivated emitter rear solar cell, comprising a silicon substrate having a front and back surface, a rear passivation layer on the back surface of the silicon substrate having a plurality of open holes formed therein, an aluminum back contact layer formed in the open holes of the rear passivation layer, and at least one backside soldering tab on the back surface of the silicon substrate. The backside soldering tab is formed from an electroconductive paste composition comprising conductive metallic particles, at least one lead-free glass frit, and an organic vehicle comprising at least one silicone oil.