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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Summary of the clip:
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
More Highlights from the same talk.
00:02:35.195 - 00:03:34.565
Why does your UV-curing process fail on PET substrates? The answer might be in your wavelength.
Why does your UV-curing process fail on PET substrates? The answer might be in your wavelength.
UV curing adhesives for flexible electronics often rely on photoinitiators activated by distinct wavelengths, typically 365, 395, or 405 nanometers. The choice of wavelength is not arbitrary; it is critically dependent on the transmission properties of the substrates being used in the device stack, a crucial consideration for roll-to-roll processing.
A common flexible substrate, Polyethylene terephthalate (PET), exhibits significant UV absorption at lower wavelengths. For a 150-micron PET foil, transmission drops dramatically below 400 nm. At 365 nm, the light intensity reaching the adhesive is often insufficient for a complete and reliable cure, leading to process failure.
The solution is to shift to a longer wavelength where the substrate is more transparent. At 405 nm, approximately 80% of the light can pass through the PET foil, ensuring sufficient energy reaches the photoinitiators to effectively polymerize the adhesive. This makes 405 nm the recommended wavelength for achieving a robust cure through PET-based substrates.
In this short video, you can learn:
* The importance of matching UV curing wavelength to substrate transmission properties.
* Why lower UV wavelengths (like 365 nm) are ineffective for curing through PET films.
* The optimal wavelength (405 nm) for UV curing adhesives on PET substrates.
š **Clip Abstract** Learn the critical relationship between UV curing wavelength and the optical properties of flexible substrates like PET. Discover why 405 nm is the optimal choice for ensuring a complete cure, a crucial factor for reliable manufacturing of flexible solar cells.
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#UVCuring, #PETSubstrates, #WavelengthOptimization, #FlexibleElectronicsAdhesives, #FlexibleSolarCells, #PrintedElectronics
00:08:41.205 - 00:09:45.695
Can you replace complex busbars and printed contacts with a simple drop of adhesive?
Can you replace complex busbars and printed contacts with a simple drop of adhesive?
Beyond simple lamination, adhesives can play an active, functional role in the electrical architecture of flexible solar cells. One innovative concept involves using electrically conductive adhesives (ECAs) to create z-axis interconnects, directly contacting the active layers of the OPV cell through the top substrate.
This process could involve creating a micro-via through the top foil, for example with a laser, and then precisely dispensing the ECA to connect the internal electrode to an external circuit. This approach could simplify manufacturing and improve the overall device design by enabling new, more efficient contacting strategies compared to traditional methods.
The material requirements for such an ECA are demanding. It must cure at low temperatures to avoid damaging the sensitive OPV materials, achieve high conductivity (requiring a high silver filler content), and, crucially, remain flexible after curing to match the mechanics of the overall device. Balancing these thermal, electrical, and mechanical properties is key to realizing this advanced manufacturing concept.
In this short video, you can learn:
* A novel concept for contacting OPV cells using electrically conductive adhesives (ECAs).
* The potential manufacturing process involving laser-drilled vias and ECA dispensing.
* The key material challenges: low-temperature cure, high conductivity, and post-cure flexibility.
š **Clip Abstract** Discover a forward-looking concept for creating electrical contacts in flexible solar cells using electrically conductive adhesives. This clip outlines a potential manufacturing process for z-axis interconnects and details the significant material challenges that must be overcome.
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#ElectricallyConductiveAdhesives, #ZAxisInterconnects, #OPVContacting, #LaserViaDrilling, #FlexibleElectronics, #PrintedElectronics
00:04:43.215 - 00:05:29.875
How do you create a flexible electronic device that's also tough enough to survive in the real world?
How do you create a flexible electronic device that's also tough enough to survive in the real world?
For OPV and perovskite solar cells, the lamination adhesive serves a critical protective function. These photovoltaic materials are highly sensitive to degradation from moisture and oxygen, so the adhesive must provide excellent barrier properties to prevent ingress and ensure long-term device stability and lifetime.
This high barrier performance is typically achieved through a densely cross-linked polymer network. However, a high degree of cross-linking often leads to a rigid, brittle material, which is fundamentally at odds with the primary requirement of flexible electronics: the ability to bend and conform without mechanical failure.
The core materials science challenge is therefore to engineer an adhesive that reconciles these conflicting properties. It requires developing a polymer chemistry that creates a sufficient barrier to water and oxygen while simultaneously incorporating molecular structures that impart inherent flexibility to the cured material. This balance is the key to enabling robust, long-lasting flexible solar cells.
In this short video, you can learn:
* The critical need for barrier properties in adhesives for OPV and perovskite encapsulation.
* The fundamental trade-off between high barrier performance (rigidity) and flexibility.
* The materials science challenge of designing polymers that are both flexible and protective.
š **Clip Abstract** Explore the central materials science challenge in adhesives for flexible photovoltaics: achieving excellent moisture and oxygen barrier properties without sacrificing flexibility. This clip explains the inherent conflict between a rigid, protective polymer network and the need for a bendable end-product.
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#FlexiblePhotovoltaics, #EncapsulationAdhesives, #MoistureOxygenBarrier, #PolymerDesign, #FlexibleElectronics, #PrintedElectronics