Back-contact solar cell electrode paste composition
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Solution Overview
Problem
Back contact solar cells face challenges in achieving low electrical resistance on both p-layer and n-layer electrodes, which affects the overall efficiency of the solar cell.
Innovation Solution
A method involving the use of a conductive paste comprising silver, palladium, and additional metals like molybdenum or boron, along with glass frit, applied to both the n-layer and p-layer, and then fired to form electrodes with sufficient electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive paste containing Ag powders and metal particles is used to form electrodes on both p-layer and n-layer, then electrical conductivity is improved, but achieving sufficiently low contact resistance on both layers simultaneously remains difficult
Solution Approach 1:
The patent changes the chemical composition parameters of the conductive paste by specifically selecting additional metal particles from Mo, B, or their mixture, and controlling their content within 1-20 wt% of the total paste weight. This parameter optimization enables the electrode to achieve low contact resistance on both p-layer and n-layer simultaneously, resolving the technical contradiction between electrical property and manufacturing difficulty.
Solution Approach 2:
The patent creates a composite conductive paste material combining Ag powders (30-80 wt%), Pd powders (10-50 wt%), and additional metal particles (Mo, B, or mixture at 1-20 wt%). This multi-component composite formulation leverages the synergistic effects of different metals to achieve low contact resistance on both semiconductor layers, solving the contradiction between achieving good electrical properties and ease of manufacture.
2Ease of manufacture
If conventional conductive paste formulations are used, then manufacturing process is simple, but contact resistance on one or both layers cannot be sufficiently reduced
Solution Approach 1:
The patent optimizes the compositional parameters of the conductive paste, specifically setting Ag content at 30-80 wt%, Pd content at 10-50 wt%, and additional metal (Mo, B, or mixture) content at 1-20 wt%. This precise parameter control maintains manufacturing simplicity while achieving the critical improvement of sufficiently low contact resistance on both p-layer and n-layer.
Solution Approach 2:
The patent uses Pd particles as a copying or intermediate layer between the Ag-based conductive paste and the semiconductor substrate. This Pd copying layer facilitates better adhesion and electrical contact, enabling low contact resistance while maintaining the simplicity of the screen-printing manufacturing process.
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 solution results in a back contact solar cell with electrodes that have low contact resistance on both layers, enhancing the solar cell's electrical properties and efficiency.
Implementation Method 1
firing the applied conductive paste
Data Source
AI summary
A method for manufacturing a back-contact solar cell, comprising the steps of: (i) preparing a semiconductor substrate comprising an n-layer and a p-layer at the back side of the semiconductor substrate; (ii) applying a conductive paste on both the n-layer and the p-layer, wherein the conductive paste comprises a silver (Ag) powder, a palladium (Pd) powder, an additional metal powder selected from the group consisting of molybdenum (Mo), boron (B) and a mixture thereof, a glass frit, and an organic medium; and (iii) firing the applied conductive paste.