Lead-Tellurium Thick-Film Paste for Solar Cell Contact Penetration
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Solution Overview
Problem
Conductive pastes struggle to penetrate anti-reflective coatings on solar cells effectively, leading to impaired electron flow and weak electrical contact with the substrate, which affects the efficiency of photovoltaic devices.
Innovation Solution
A thick-film paste composition comprising 90 to 99.5% electrically conductive metal, 0.5 to 10% lead-tellurium-oxide, and an organic medium, capable of penetrating insulating layers upon firing, is used to form electrical connections with the semiconductor substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional conductive paste is used, then the anti-reflective coating provides good light absorption, but the insulating layer impairs electron flow and weakens electrical contact
Solution Approach 1:
The conductive paste composition is modified by adjusting the glass frit particle size distribution (bimodal or multimodal distribution with specific D10, D50, D90 values) and chemical composition (specific ratios of PbO, SiO2, B2O3, Al2O3, TiO2, ZnO) to enable effective penetration of the anti-reflective coating while maintaining strong electrical contact
Solution Approach 2:
The conductive paste uses a composite formulation combining multiple metal particles (silver, aluminum, copper) with specially designed glass frit and organic vehicle, creating a material that can simultaneously adhere to the substrate, penetrate the insulating layer, and provide excellent electrical conductivity
2Reliability
If the conductive paste penetrates the anti-reflective coating effectively, then electrical contact is improved, but the manufacturing complexity increases
Solution Approach 1:
While the paste composition is complex, the parameters are optimized within specific ranges (glass frit particle size D10: 0.5-2.0 μm, D50: 3-6 μm, D90: 8-15 μm; specific weight percentages of oxides) to achieve reliable penetration and contact, balancing complexity with performance
3Reliability
If the firing temperature is increased to improve penetration, then electrical contact is enhanced, but energy consumption and substrate damage risk increase
Solution Approach 1:
The glass frit composition is designed with specific melting characteristics (using PbO as flux with 30-70 wt%, combined with SiO2, B2O3, Al2O3, TiO2, ZnO) that lower the softening temperature and enable effective penetration at reduced firing temperatures (700-850°C), decreasing energy consumption while maintaining reliable electrical contact
Solution Approach 2:
The glass frit undergoes phase transition from solid to viscous liquid state during firing, enabling the conductive paste to flow and penetrate the anti-reflective coating at lower temperatures, reducing both energy consumption and substrate damage risk while ensuring good electrical contact
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 composition enables strong electrical contact and improved efficiency by penetrating anti-reflective coatings, enhancing the performance of photovoltaic devices.
Implementation Method 1
the conductive ink should penetrate the anti-reflective coating during firing to form metal contacts having electrical contact with the semiconductor substrate
Implementation Method 2
conductive pastes are printed onto a substrate as grid lines or other patterns and then fired
Data Source
Figure 1A~1F
AI summary
The present invention provides a thick-film paste for printing the front-side of a solar cell device having one or more insulating layers. The thick-film paste comprises an electrically conductive metal, and a lead-tellurium-oxide dispersed in an organic medium.