Ethylene/Alpha-Olefin Encapsulant Composition for Durable Glass Adhesion
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Solution Overview
Problem
Existing photovoltaic encapsulant films, primarily made from ethylene vinyl acetate (EVA), suffer from issues such as acid release leading to corrosion of solar cells, low volume resistivity causing potential induced degradation, and reduced adhesion to glass over time, especially under high temperature and humidity conditions.
Innovation Solution
A composition comprising ethylene/alpha-olefin/interpolymer, a peroxide, and a Si-containing compound, such as vinyl oligomericsiloxane, which promotes crosslinking and maintains high adhesive strength and volume resistivity, even after aging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ethylene vinyl acetate (EVA) is used as the encapsulant material, then the encapsulant provides good initial adhesion to glass and solar cells, but the adhesion strength deteriorates over time due to acid release and corrosion
Solution Approach 1:
The patent changes the chemical composition parameters by replacing EVA with ethylene/alpha-olefin copolymer containing terminal vinyl groups, and adjusts the crosslinking agent composition (using silane-based crosslinking agents in combination with peroxide crosslinking agents). This parameter change eliminates acid release while maintaining and improving adhesion stability over time, achieving both strong initial adhesion and long-term reliability.
Solution Approach 2:
The patent employs a composite material system combining ethylene/alpha-olefin copolymer with terminal vinyl groups, silane-based crosslinking agents, and peroxide crosslinking agents. This composite approach creates a synergistic effect where the copolymer provides adhesion, silane agents provide crosslinking and stability, and peroxide agents enhance the crosslinking network, together achieving both strong initial adhesion and long-term adhesion stability without acid release.
2Reliability
If EVA is used as the encapsulant material, then the encapsulant provides good initial adhesion, but the volume resistivity is low causing potential induced degradation
Solution Approach 1:
The patent changes the material composition by replacing EVA with ethylene/alpha-olefin copolymer containing terminal vinyl groups and implementing a dual crosslinking system (silane and peroxide). This parameter change increases the volume resistivity from 10^14-10^15 ohm·cm in EVA to 10^16-10^17 ohm·cm in the new composition, thereby improving electrical insulation performance and eliminating potential induced degradation while maintaining good adhesion properties.
3Reliability
If EVA is used as the encapsulant material, then the encapsulant provides good initial adhesion, but acid is released during usage causing corrosion of solar cells and solder ribbons
Solution Approach 1:
The patent fundamentally changes the chemical composition by replacing EVA with ethylene/alpha-olefin copolymer containing terminal vinyl groups. This parameter change eliminates the vinyl acetate group that is responsible for acid release in EVA. The resulting copolymer composition is chemically stable and does not release acid during usage, thereby improving chemical stability and eliminating corrosion of solar cells and solder ribbons while maintaining good adhesion properties.
4Reliability
If magnesium hydroxide or magnesium oxide is added to prevent peroxide bleeding and hydrolysis, then the peroxide stability is improved, but the clarity of the encapsulated film deteriorates
Solution Approach 1:
The patent changes the approach to peroxide stabilization by replacing magnesium hydroxide/magnesium oxide with silane-based crosslinking agents. This parameter change eliminates the white precipitate and haze caused by magnesium compounds. The silane agents provide equivalent or superior peroxide stability during storage while maintaining excellent film clarity and optical transparency, achieving both peroxide stability and optical quality.
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 provides strong adhesion to glass, maintains high volume resistivity, and exhibits good curing properties, ensuring durability and electrical insulation of solar cell modules.
Implementation Method 1
a peroxide; c) a 'Si-containing compound' selected from the following i) through v): i) a vinyl oligomericsiloxane; iv) a vinyl oligomericsiloxane
Implementation Method 2
c) a 'Si-containing compound' selected from the following i) through v): i) a vinyl oligomericsiloxane; iv) a vinyl oligomericsiloxane
Implementation Method 3
b) a peroxide; c) a 'Si-containing compound' selected from the following i) through v): i) a vinyl oligomericsiloxane
Data Source
AI summary
A composition comprising the following: a) an ethylene/alpha-olefin/interpolymer; b) a peroxide; c) a “Si-containing compound” selected from the following (i) through (v): (i), where each R is independently selected from a C1-C3 alkyl, and n is from 1 to 16; (ii), where each R is independently methyl or ethyl, and n is from 1 to 18; (iii), where each R is independently methyl or ethyl; (iv) a vinyl oligomericsiloxane; or (v) any combination of (i) through (iv).