Lena Reinke | Hoenle Adhesives: Beyond simple elongation at break, what hidden factors truly govern the "flexibility" of thin-film PV adhesives?
00:05:00 - 00:05:17
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Beyond simple elongation at break, what hidden factors truly govern the "flexibility" of thin-film PV adhesives?
The concept of flexibility in adhesives for thin-film applications, such as flexible photovoltaics, is more complex than a singular metric like elongation at break. Flexibility encompasses various mechanical responses, including bonding strain and tensile strain, which may not directly correlate. A material with low elongation at break can still exhibit excellent bondability and flexibility when applied as a thin layer, particularly when bonded to flexible substrates like PET foils.
The apparent flexibility of a material is significantly influenced by its thickness. Thinner layers inherently appear more flexible, even if the bulk material properties suggest otherwise. This phenomenon is observed in materials like Indium Tin Oxide (ITO), which can be quite flexible in thin-film form. Therefore, when evaluating adhesives for flexible PV, it is crucial to consider the adhesive layer thickness and its interaction with the flexible substrates, rather than solely relying on bulk material properties.
In this short video, you can learn:
* Flexibility is a multi-faceted property, not solely defined by elongation at break.
* Distinction between bonding strain and tensile strain.
* The critical role of material thickness in perceived flexibility.
* Examples of thin films (e.g., ITO) demonstrating enhanced flexibility.
#ThinFilmPVAdhesives, #AdhesiveFlexibility, #MaterialThicknessEffect, #ElongationAtBreak, #FlexiblePhotovoltaics, #FlexibleElectronics
This is a highlight of the presentation:
Advanced Bonding Technologies for Flexible Substrates and Electronic Devices
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00:02:49 - 00:04:01
How can UV light, a known degradant for PV cells, be simultaneously essential for their flexible encapsulation?
How can UV light, a known degradant for PV cells, be simultaneously essential for their flexible encapsulation?
UV irradiation, spanning roughly 100 to 400 nanometers, is a segment of the electromagnetic spectrum that photovoltaic cells are typically shielded against to prevent degradation. However, in the context of adhesive curing for flexible PV applications, specific UV wavelengths, such as 405 nanometers, are intentionally employed. This distinction is crucial: while the PV cell itself requires protection from broad-spectrum UV, the bonding process leverages targeted UV light for rapid and efficient polymerization of specialized adhesives.
The curing systems, like those offered by LER, utilize powerful UV LED light sources designed for precise wavelength emission. These units can be configured in various geometries—line, rectangle, or circular—and are stackable to create uniform irradiation fields without gaps. Modern systems are often air-cooled, enhancing their integration into industrial roll-to-roll processes, which are critical for high-throughput manufacturing of flexible photovoltaic devices.
In this short video, you can learn:
* The dual role of UV light in photovoltaics: degradation vs. curing.
* The specific wavelength (e.g., 405nm) used for UV adhesive curing.
* Features of industrial UV curing equipment, including power, geometry, and cooling.
* The importance of rapid curing for flexible PV manufacturing.
#UVAdhesiveCuring, #FlexiblePhotovoltaics, #UVLEDSystems, #RollToRollProcessing, #PhotovoltaicEncapsulation, #SemiconductorManufacturing
00:06:22 - 00:08:00
Is it fundamentally impossible to achieve both high flexibility and superior moisture barrier performance in PV encapsulants?
Is it fundamentally impossible to achieve both high flexibility and superior moisture barrier performance in PV encapsulants?
Water Vapor Transmission Rate (WVTR) is a critical metric for photovoltaic encapsulants, quantifying the amount of water vapor that permeates through a material over time, typically measured in accordance with ASTM norms. A lower WVTR value signifies superior barrier performance, which is essential for protecting moisture-sensitive PV components, particularly perovskite solar cells, from environmental degradation. High-performing adhesives can achieve WVTR values as low as 8, indicating excellent moisture resistance.
There exists an inherent inverse relationship between an adhesive's flexibility and its water vapor barrier properties. Highly flexible polymeric networks generally possess a lower cross-linking density, resulting in larger molecular voids that facilitate the permeation of small water molecules. Conversely, stiffer materials exhibit higher cross-linking densities and smaller voids, thereby impeding water transmission more effectively. This trade-off necessitates careful material selection and formulation to balance mechanical demands with environmental protection in flexible PV applications.
In this short video, you can learn:
* Definition and significance of Water Vapor Transmission Rate (WVTR) for PV.
* How WVTR is measured according to ASTM standards.
* The inverse correlation between material flexibility and WVTR.
* The role of cross-linking density and molecular voids in water permeation.
#PVEncapsulants, #MoistureBarrier, #MaterialFlexibility, #WVTR, #PerovskiteSolar, #FlexiblePV