Solar Cell Electrode Paste with Amide Thickener
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Solution Overview
Problem
Existing solar cell electrode compositions face challenges in achieving low contact resistance and series resistance while maintaining high efficiency, particularly as the area of solar cells increases, and they struggle with thermal stability across different wafers with varying sheet resistances.
Innovation Solution
A composition for forming a solar cell electrode comprising a conductive silver powder, glass frit, and an organic vehicle with a specific thickener, binder resin, and solvent, which includes a mono-amide or bis-amide-based thickener to enhance viscoelasticity and printing characteristics, and a glass frit with varying transition temperatures to ensure adhesion and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the area of solar cells is increased, then the power output is improved, but the contact resistance and series resistance increase
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrode paste by incorporating specific organic vehicles with controlled viscosity and rheological properties. This allows the paste to maintain optimal electrical contact characteristics across larger solar cell areas, preventing the increase in contact resistance that typically occurs with area expansion.
Solution Approach 2:
The patent uses a composite organic vehicle system combining multiple components including viscosifiers, solvents, and binders in specific ratios. This composite formulation creates an electrode paste that maintains both low contact resistance and low series resistance simultaneously, resolving the contradiction between power output and electrical resistance in large-area solar cells.
2Strength
If the firing temperature is increased, then the adhesion is improved, but the thermal stability deteriorates
Solution Approach 1:
The patent optimizes the firing temperature parameter within a specific range (700-900°C) and combines it with an organic vehicle formulation that contains components designed to decompose and form a stable glass matrix at these temperatures. This resolves the contradiction by achieving sufficient adhesion through controlled thermal processing while maintaining overall thermal stability of the electrode structure.
Solution Approach 2:
The organic vehicle acts as an intermediary material that facilitates adhesion between the conductive powder and the substrate during firing. Its specific composition including glass formers and binders creates a bonding interface that achieves strong adhesion at moderate firing temperatures without requiring excessive heat that would compromise thermal stability.
3Manufacturing precision
If the viscosity of the organic vehicle is increased, then the printability is improved, but the flowability deteriorates
Solution Approach 1:
The patent employs rheological modifiers in the organic vehicle that provide shear-thinning behavior. The paste maintains higher viscosity at rest to ensure good printability and pattern definition, but exhibits reduced viscosity during the printing process to ensure adequate flowability and complete filling of the electrode pattern, thus resolving the contradiction between printability and flowability.
Solution Approach 2:
The patent carefully balances the viscosity parameters of the organic vehicle by selecting specific viscosifiers and their concentrations. This creates a viscosity profile that provides sufficient thickness for precise printing while maintaining enough fluidity for proper flow and leveling, resolving the trade-off between printability and flowability.
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 achieves low contact resistance, improved printability, and enhanced solar cell efficiency by minimizing series resistance and maintaining electrical characteristics, while allowing for a wide range of firing temperatures and substrate compatibility.
Implementation Method 1
a glass frit with varying transition temperatures to ensure adhesion and thermal stability
Implementation Method 2
a specific thickener, binder resin, and solvent, which includes a mono-amide or bis-amide-based thickener to enhance viscoelasticity and printing characteristics
Implementation Method 3
Solar cells generate electrical energy using the photovoltaic effect of a p-n junction that converts photons of sunlight into electricity
Data Source
AI summary
A composition for forming an electrode for a solar cell includes a conductive powder, a glass frit, and an organic vehicle, the organic vehicle including a thickener including a structural unit represented by Chemical Formula 1,