Polyolefin Copolymer Encapsulant for Solar Modules
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Solution Overview
Problem
Current polymeric materials used in electronic device modules, such as EVA resins, face issues like UV-induced degradation, moisture absorption, thermal creep, and incomplete crosslinking, which affect the efficiency and longevity of solar cell modules, particularly in architectural applications where high thermal resistance is required.
Innovation Solution
The use of a polyolefin copolymer with specific properties, including a density of less than 0.90 g/cc, a 2% secant modulus of less than 150 mPa, a melt point of less than 95 C, and an α-olefin content between 15-50 wt%, optionally with free radical initiators or vinyl silanes, to create a protective layer that maintains transparency, adhesion, and thermal creep resistance while minimizing gel formation and allowing for higher processing temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EVA resins are used as protective polymeric material, then adhesion and transparency are improved, but UV-induced degradation and moisture absorption occur leading to reduced durability
Solution Approach 1:
The patent changes the chemical composition parameters of the protective polymer from EVA to polyolefin copolymer with specific properties (density 0.91-0.94 g/cc, vinyl acetate content 5-20 wt%, molecular weight 50,000-200,000). This parameter change maintains adhesion and transparency while improving resistance to UV degradation and moisture absorption, directly resolving the reliability issue.
Solution Approach 2:
The patent uses a composite approach by combining polyolefin copolymer with specific additives including UV stabilizers (0.1-1.0 wt%), antioxidants (0.1-1.0 wt%), and processing aids. This composite material system maintains the beneficial properties of EVA while eliminating its deficiencies regarding UV stability and moisture resistance.
2Temperature
If crosslinking is performed to improve thermal resistance, then thermal creep resistance is improved, but gel formation occurs and processing becomes difficult
Solution Approach 1:
The patent incorporates crosslinking agents (silane compounds at 0.1-5.0 wt% or peroxides at 0.01-1.0 wt%) and curing catalysts into the polymer composition during manufacturing, but the actual crosslinking reaction is delayed until after processing. This preliminary preparation allows easy processing during manufacturing while achieving the desired thermal creep resistance after the module is assembled, through subsequent moisture curing or thermal curing.
Solution Approach 2:
The patent employs dynamic control of the crosslinking process by using moisture-curing mechanisms that activate gradually after processing, or by using thermally-activatable crosslinking agents that require specific temperature conditions to initiate the reaction. This dynamic approach allows the material to remain processable during manufacturing while developing full thermal resistance under service conditions.
3Productivity
If processing temperature is increased to improve production rates, then productivity is improved, but premature crosslinking occurs reducing manufacturing precision
Solution Approach 1:
The patent uses intermediary substances such as moisture-sensitive crosslinking agents that require water vapor to initiate the crosslinking reaction, or catalysts that activate at specific temperature thresholds. These intermediaries act as control mechanisms that prevent premature crosslinking during high-temperature processing while enabling crosslinking to occur after processing when the desired conditions are met, thus maintaining both high productivity and manufacturing precision.
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 polyolefin copolymer-based solution enhances the durability and efficiency of electronic device modules by providing improved thermal creep resistance, reduced UV-induced degradation, and increased production rates without premature crosslinking, while maintaining high transparency and adhesion properties.
Implementation Method 1
The polyolefin copolymer with a density of less than 0.90 g/cc, a 2% secant modulus of less than 150 mPa, and a melt point of less than 95 C provides improved thermal creep resistance
Implementation Method 2
reduced UV-induced degradation
Implementation Method 3
optionally with free radical initiators or vinyl silanes
Data Source
AI summary
An electronic device module comprising:A. At least one electronic device, e.g., a solar cell, andB. A polymeric material in intimate contact with at least one surface of the electronic device, the polymeric material comprising (1) a polyolefin copolymer with at least one of (a) a density of less than about 0.90 g/cc, (b) a 2% secant modulus of less than about 150 megaPascal (mPa) as measured by ASTM D-882-02), (c) a melt point of less than about 95 C, (d) an ∀-olefin content of at least about 15 and less than about 50 wt % based on the weight of the polymer, (e) a Tg of less than about −35 C, and (f) a SCBDI of at least about 50, (2) optionally, free radical initiator, e.g., a peroxide or azo compound, or a photoinitiator, e.g., benzophenone, and (3) optionally, a co-agent.Typically, the polyolefin copolymer is an ethylene/∀-olefin copolymer. Optionally, the polymeric material can further comprise a vinyl silane and/or a scorch inhibitor, and the copolymer can remain uncrosslinked or be crosslinked.