Silane-Grafted Ethylene Films for PID-Resistant PV Encapsulation
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Solution Overview
Problem
Current polymeric materials used in low-current electronic devices, such as photovoltaic modules, face challenges in providing optimal insulation and electrical resistance, leading to inefficiencies in current recovery and storage due to issues like electrical leakage and mechanical stress during curing.
Innovation Solution
Development of silane-grafted ethylene interpolymer films with specific density, alkoxysilane content, and crosslinking properties, using a catalyst system excluding boron-containing cocatalysts, to enhance electrical insulation and adhesion while minimizing residual impurities and mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polymeric materials are used for encapsulation, then processing and sealing are easier, but electrical insulation and resistance are insufficient leading to current leakage
Solution Approach 1:
The patent changes the chemical composition parameters of the polymeric material by incorporating silane-containing ethylene interpolymer with specific density (0.85-0.90 g/cm³) and alkoxysilane content (0.1-5.0 wt%), which fundamentally alters the electrical properties while maintaining processability
Solution Approach 2:
The invention creates a composite material system combining ethylene interpolymer base resin with grafted alkoxysilane groups, forming a hybrid structure that integrates the processability of conventional polymers with the superior electrical insulation properties of silane-modified networks
2Reliability
If polymeric materials with high electrical resistance are used, then current leakage is reduced, but adhesion to substrates and devices deteriorates
Solution Approach 1:
The patent applies local quality modification by grafting alkoxysilane groups at specific locations within the polymeric structure, creating regions with enhanced adhesion properties while the bulk material maintains high electrical resistance characteristics
Solution Approach 2:
The silane-containing ethylene interpolymer acts as an intermediary material that bridges the gap between substrate surfaces and encapsulation layers, providing both chemical bonding capability for adhesion and electrical insulation properties through its molecular structure
3Reliability
If curing is performed to improve adhesion and insulation, then mechanical stress from polymer shrinkage damages the electronic device, but without curing adhesion and insulation are insufficient
Solution Approach 1:
The patent modifies the curing parameters and polymerization conditions to control the degree of crosslinking and shrinkage, optimizing the balance between achieving sufficient adhesion through curing and minimizing mechanical stress on embedded devices
Solution Approach 2:
The invention incorporates flexible segments and controlled unsaturation in the ethylene interpolymer structure beforehand to cushion and absorb the mechanical stress generated during curing, preventing transmission of harmful forces to the electronic device
4Productivity
If boron-containing cocatalysts are used in polymerization, then polymerization efficiency is improved, but residual boron decreases electrical insulation and increases PID
Solution Approach 1:
The patent extracts and eliminates boron-containing cocatalysts from the polymerization system, replacing them with alternative catalyst systems that do not leave harmful residues, thereby preserving polymerization efficiency while improving electrical insulation properties
Solution Approach 2:
The invention employs disposable, boron-free catalyst systems that can be completely removed or decomposed after polymerization, leaving no persistent residual boron in the final product, thus maintaining both productivity and electrical performance
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 silane-grafted ethylene interpolymer films demonstrate improved electrical insulation with high volume resistivity and reduced potential-induced degradation (PID) in photovoltaic modules, maintaining efficiency and durability.
Implementation Method 1
high electrical resistance with little, if any, electrical conductance
Implementation Method 2
containing at least 5 percent crosslinked interpolymer as measured by gel content
Data Source
Figure 1~2
Figure 3
AI summary
Disclosed in more detail in this application are ethylene interpolymer films having one or more layers, comprising surface layer comprising: (A) a silane-containing ethylene interpolymer comprising (1) an ethylene interpolymer having a density of less than 0.905 g/cm3, and (2) at least 0.1 percent by weight alkoxysilane; characterized by: (3) having a volume resistivity of greater than 5 x 1015 ohm-cm as measured at 60C. In one embodiment, such ethylene interpolymer has a residual boron content of less than 10 ppm and residual aluminum content of less than 100 ppm. Also disclosed are laminated electronic device modules comprising: A. at least one electronic device, and B. one of the ethylene interpolymer films as described above in intimate contact with at least one surface of the electronic device. Such laminated electronic device modules according to the invention have been shown to suffer reduced potential induced degradation ("PID").