Conductive Paste Bus Bar Adhesion on Passivation Films
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Solution Overview
Problem
Conductive pastes used in crystalline silicon solar cells face challenges in achieving high adhesive strength on passivation films without detrimental effects, leading to reduced solar cell performance due to fire-through reactivity and surface defects.
Innovation Solution
A conductive paste containing silver particles, an organic vehicle, and glass frit with specific compositions of TeO2, Bi2O3, and optional oxides like SiO2, ZnO, and TiO2, which inhibits fire-through reactivity and enhances adhesive strength on passivation films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductive paste with high fire-through reactivity is used, then good electrical contact is achieved, but surface defects occur and solar cell performance decreases
Solution Approach 1:
The patent modifies the chemical composition parameters of glass frit by incorporating specific metal oxides (Bi2O3 at 10-30 mol%, TeO2 at 1-20 mol%, ZnO at 5-30 mol%) to adjust the reactivity characteristics. This parameter change enables the conductive paste to achieve adequate electrical contact while suppressing excessive fire-through reactivity that causes surface defects
Solution Approach 2:
The patent creates a composite glass frit system combining multiple oxide components (Bi2O3, TeO2, ZnO, SiO2, B2O3) that work synergistically. This composite material provides both the necessary reactivity for electrical contact formation and the stability to prevent harmful fire-through effects, resolving the contradiction between contact quality and surface integrity
2Strength
If glass frit with high reactivity is used to ensure good adhesion, then adhesive strength increases, but fire-through reactivity causes detrimental effects on passivation films
Solution Approach 1:
The patent adjusts the chemical composition parameters of glass frit by incorporating specific metal oxides (Bi2O3 at 10-30 mol%, TeO2 at 1-20 mol%, ZnO at 5-30 mol%) to adjust the reactivity characteristics. This parameter change enables the conductive paste to achieve adequate electrical contact while suppressing excessive fire-through reactivity that causes surface defects
Solution Approach 2:
The composite glass frit acts as an intermediary material between the conductive paste and the passivation film. It provides sufficient adhesion for electrode formation while its controlled reactivity prevents harmful fire-through effects, mediating between the conflicting requirements of strong bonding and low reactivity
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 conductive paste achieves high adhesive strength for bus bar electrodes on passivation films, preventing surface defects and maintaining solar cell performance by controlling reactivity and ensuring non-detrimental effects on the passivation films during firing.
Implementation Method 1
glass frit... forming an ohmic junction between the conductive ink and semiconductor by penetrating through the antireflection film during firing
Implementation Method 2
electrodes formed by coating a conductive paste... onto a semiconductor substrate... followed by firing
Data Source
AI summary
Provided is a conductive paste for forming bus bar electrodes having high adhesive strength with respect to a passivation film in a crystalline silicon solar cell without having a detrimental effect on the passivation film so as to affect solar cell properties.The conductive paste is a conductive paste formed on a passivation film of a solar cell, containing: (A) silver particles, (B) an organic vehicle, and (C) glass fit containing TeO2 at 1.0 mol % to 20 mol % and Bi2O3 at 10 mol % to 30 mol %.