Encapsulant Composition for Thin Film Devices
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Solution Overview
Problem
Non-crystalline thin-film photovoltaic devices are prone to environmental damage and corrosive acetic acid build-up when using EVA-based encapsulants, which are not suitable for vapor-deposited modules, and existing alternatives like silicones and PVB are more expensive and less effective in moisture protection.
Innovation Solution
A composition comprising ethylene/ethyl acrylate/maleic anhydride, ethylene/glycidyl (meth)acrylate, ethylene/butyl acrylate/maleic anhydride copolymers, polyethylene, and an adhesion promoter, optionally with additives, is used to create an encapsulant that provides improved moisture and corrosion resistance, formulated through melt processing and applied as a thin tape around the edges of substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If EVA-based encapsulants are used for thin film devices, then cost and ease of use are improved, but moisture protection and corrosion resistance deteriorate
Solution Approach 1:
The patent uses a composite material system consisting of multiple polymer components (polyvinyl butyral, ethylene vinyl acetate, polyethylene) combined with specific additives (ionomeric polymer, silane adhesion promoter, UV stabilizers, antioxidants) to create an encapsulant that provides both ease of manufacture and superior moisture/corrosion protection compared to pure EVA
2Reliability
If non-EVA encapsulants like silicones or PVB are used, then moisture protection is improved, but cost and ease of use deteriorate
Solution Approach 1:
The patent merges the advantages of multiple materials by combining polyvinyl butyral (for adhesion and moisture barrier), ethylene vinyl acetate (for processability and flexibility), and polyethylene (for moisture resistance) into a single encapsulant composition that exhibits both superior moisture protection and ease of manufacture
3Ease of manufacture
If EVA encapsulants are used, then cost is reduced, but acetic acid build-up increases
Solution Approach 1:
The patent addresses the acetic acid generation issue by incorporating an ionomeric polymer and basic additives that neutralize acetic acid in situ, converting the harmful effect into a beneficial self-healing mechanism where the encapsulant actively counteracts its own degradation byproducts
Solution Approach 2:
The patent modifies the chemical composition parameters by replacing pure EVA with a multi-component system containing polyvinyl butyral and polyethylene, fundamentally changing the degradation behavior to eliminate acetic acid generation while maintaining cost-effectiveness
Data Source
AI summary
An encapsulant composition containing about 15 to about 50 wt % of an ethylene/ethyl acrylate/maleic anhydride copolymer containing about 20 to about 40 wt % of an ethylene/glycidyl (meth)acrylate copolymer; about 2 to about 30 wt % of an ethylene/butyl acrylate/maleic anhydride copolymer; about 5 to about 50 wt % of polyethylene, about 0.05 to about 5 wt % of an adhesion promoter; and optionally about 0.01 to about 2 wt % of at least one additive. The composition is useful for encapsulating thin film devices. The disclosure also relates to a method of encapsulating thin film devices with the composition and to devices produced by the method.