Tackifier-Based Paste Composition for Solar Cell Backside Electrode Adhesion
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Solution Overview
Problem
The adhesive property of the backside electrode in solar cell elements can be compromised, leading to the exfoliation of the aluminum electrode layer, which affects the efficiency and reliability of the solar cell, particularly due to variations in the surface state of the silicon semiconductor substrate.
Innovation Solution
A paste composition comprising aluminum powder, an organic vehicle, and a tackifier, such as polypropylene-based resin, is used to enhance the adhesive property of the aluminum electrode layer, preventing exfoliation by improving the bonding between the electrode and the substrate without increasing the organic vehicle content excessively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the organic vehicle content in the paste composition is increased to improve adhesion, then the adhesive property improves, but the drying time increases and the firing process becomes less efficient
Solution Approach 1:
The patent changes the chemical composition parameters of the organic vehicle by introducing a specific mixture of carboxylic acid and its ester. This chemical parameter change allows the paste to achieve adequate adhesion with reduced organic vehicle content, thereby reducing drying time while maintaining reliable bonding between the aluminum electrode layer and silicon substrate.
Solution Approach 2:
The patent uses a composite organic vehicle system combining carboxylic acid and its ester in specific proportions. This composite approach creates synergistic effects where the carboxylic acid provides strong bonding to the silicon substrate while the ester component ensures proper paste rheology and adhesion, achieving effective adhesion without excessive organic vehicle content that would extend drying time.
2Reliability
If the paste composition is optimized for adhesion, then the aluminum electrode layer bonding improves, but the manufacturing complexity increases
Solution Approach 1:
The patent optimizes specific parameters of the organic vehicle (carboxylic acid content at 1-20% and ester content at 5-80%) to achieve the desired bonding strength. By carefully controlling these compositional parameters, the patent obtains adequate adhesion with a relatively simple paste formulation, avoiding excessive manufacturing complexity while ensuring reliable bonding between the aluminum electrode layer and silicon substrate.
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 use of the tackifier-based paste composition significantly improves the adhesive property and production yield of solar cell elements by maintaining the aluminum electrode layer's integrity and enhancing the energy conversion efficiency.
Implementation Method 1
the use of a paste composition having a specific composition makes it possible to attain the above-mentioned object... improvement in the adhesive property of a backside electrode
Implementation Method 2
aluminum diffuses into the p type silicon semiconductor substrate 1, thereby forming an Al—Si alloy layer 6 between the aluminum electrode layer 5 and the p type silicon semiconductor substrate 1
Implementation Method 3
applying a paste composition composed of aluminum powder, glass frit and an organic vehicle by screen printing or the like, drying the composition and then firing the resultant
Data Source
AI summary
Provided are a paste composition making it possible to improve the adhesive property of a backside electrode and restrain an aluminum electrode layer from exfoliating, and a solar cell element having an electrode formed by use of this composition. The paste composition is a paste composition for forming an electrode (8) on a silicon semiconductor substrate (1) which comprises aluminum powder, an organic vehicle, and a tackifier. The solar cell element has the electrode (8) formed by painting a paste composition having the above-mentioned characteristic onto the silicon semiconductor substrate (1) and then firing the resultant.