Whitney Gaynor | Sinovia Technologies: Why does a higher ink viscosity produce a smoother printed OLED film?
00:15:16.775 - 00:16:01.075
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Summary of the clip:
Can high-throughput roll-to-roll printing achieve sub-micron surface smoothness when ink leveling time is virtually eliminated?
In high-speed roll-to-roll (R2R) printed electronics, conventional rheological assumptions regarding ink leveling are challenged by extreme process dynamics. While low-viscosity formulations typically rely on post-deposition surface tension to level out printed features, high-speed web handling compresses the available window for fluid relaxation to near zero. Under these conditions, higher viscosity inks can paradoxically yield superior film smoothness by preserving the structural integrity of the wet deposit and resisting shear-induced deformation prior to solidification.
The integration of hybrid curing mechanisms is essential to freeze these highly engineered microstructures before film defects can propagate. By incorporating ultraviolet (UV) curable components into critical functional layers, such as the anode, developers can initiate near-instantaneous photopolymerization. This rapid phase transition locks in the desired morphology, whereas subsequent non-UV active layers, such as the light-emitting formulation, must rely on alternative rapid-drying kinetics compatible with the overall thermal budget of the substrate.
Operating at line speeds of 18 meters per minute reduces the total dwell time within the drying and curing zones to under one second. This sub-second processing window demands meticulous formulation engineering, where solvent evaporation, UV crosslinking, and polymer diffusion must occur almost simultaneously on a continuously moving web. Consequently, material selection is dictated not just by optoelectronic performance, but by the strict temporal constraints of the inline manufacturing equipment.
In this short video, you can learn:
* Why high-viscosity formulations can prevent film defects and improve surface smoothness when ink leveling time is eliminated.
* The role of hybrid UV-curable and non-UV layers in managing phase transitions on a continuously moving web.
* How to engineer functional ink formulations to survive sub-second curing and drying windows at high line speeds.
π **Clip Abstract**
The speaker explains that high-viscosity formulations yield smoother films on their printing press because the high web speed of 18 meters per minute leaves no time for ink leveling. To accommodate a sub-second curing window on the continuously moving web, the process utilizes a UV-curable anode layer alongside a non-UV light-emitting layer.
π€ Speaker: Whitney Gaynor
π’ Company: Sinovia Technologies
π
Event: The Future of Electronics RESHAPED 2023 Berlin
π Location: Estrel Congress Centre, Berlin, Germany, Europe
π Learn more at the next TechBlick event: https://www.techblick.com
#MarangoniEffect, #InkRheology, #Flexography, #RollToRollPrinting, #PrintedOLED, #FlexibleElectronics
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00:03:15.025 - 00:04:37.655
How can you print nanoscale-smooth OLED anodes on flexible substrates without damaging the barrier layers?
How can you print nanoscale-smooth OLED anodes on flexible substrates without damaging the barrier layers?
Sinovia Technologies' core innovation is a silver nanowire-based, transparent, conductive film that can be printed roll-to-roll at 100-micron resolution directly onto an ultra-barrier. This serves as the foundational anode layer for bottom-emitting OLED displays, eliminating the need for laser patterning (which produces particles) or photolithography (which can damage the underlying barrier film).
By controlling the structure and utilizing nanoscale-smooth films, subsequent thin organic transport and emitter layers can be deposited uniformly on top. This approach allows high-yield, flexible, segmented, or passive matrix displays to be fabricated continuously from roll to roll.
In this short video, you can learn:
* How silver nanowire networks form a smooth, high-resolution anode directly on flexible ultra-barriers.
* Why roll-to-roll printing avoids the barrier damage typical of photolithography and laser patterning.
* The spatial resolution limit of flexographic printed anodes and its implications for display density.
π **Clip Abstract** Sinovia Technologies uses roll-to-roll flexography to print silver nanowire anodes directly on ultra-barrier films at 100-micron resolution. This avoids the defect risks of laser patterning and lithography, creating a nanoscale-smooth foundation for subsequent OLED layers.
#SilverNanowires, #RollToRollFlexography, #PrintedAnodes, #UltraBarrier, #FlexibleOLED, #PrintedElectronics
00:07:55 - 00:09:01
How do you prevent microscale ink splitting from ruining nanometer-scale OLED layers?
How do you prevent microscale ink splitting from ruining nanometer-scale OLED layers?
When transitioning flexographic printing to optoelectronic devices, the physics of ink transfer presents a critical barrier. As ink separates from the flexo plate to the substrate, the liquid meniscus splits, triggering the formation of viscous fingers in the cross-web direction.
In standard graphic arts, this surface perturbation is harmless; however, for OLED architectures, these sub-micron periodic thickness variations propagate directly through the entire device stack. This non-uniformity alters the local electric field, leading to spatial variations in light emission and premature device degradation.
Overcoming this requires modeling and controlling multiple coupled variables. The ink's viscoelastic properties, printing speed, and roll surface textures must be precisely engineered to force the printed film to level before drying.
In this short video, you can learn:
* The fluid dynamics of liquid meniscus splitting and the formation of cross-web viscous fingers.
* Why periodic thickness variations cause non-uniform emission and shorter device lifetimes.
* The multi-variable approach needed to eliminate mechanical print features in thin-film optoelectronics.
π **Clip Abstract** This clip details the fluidic challenges of adapting high-speed contact printing to nanometer-scale electronic devices. It explains how viscous fingering during ink transfer damages OLED uniformity and the strategy required to resolve it.
π Link in comments π
#ViscousFingering, #FlexographicPrinting, #InkSplitting, #OLEDManufacturing, #PrintedElectronics, #FlexibleElectronics
00:08:17.925 - 00:09:28.895
How do you prevent "viscous fingering" from ruining printed OLED layers?
How do you prevent "viscous fingering" from ruining printed OLED layers?
Unlike non-contact methods like inkjet or slot-die coating, flexography is a contact printing technology where ink transfer relies on fluid splitting. As the ink separates from the printing plate to the web, physical phenomena like viscous fingering create ribbing and non-uniformities at a specific wavelength, frequency, and amplitude.
For OLEDs, which require ultra-thin organic layers on the nanometer scale, these surface perturbations are highly detrimental and must dry perfectly flat. Mitigating this challenge requires precise co-optimization of flexographic plate materials, ink formulation, and anilox cylinder volumes to ensure self-leveling before curing.
In this short video, you can learn:
* The physics of ink splitting and the root causes of viscous fingering in roll-to-roll contact printing.
* Why thickness uniformities on the nanometer scale are uniquely challenging for printed electronic layers.
* The critical parametersβsuch as plate materials and anilox volumesβused to manage film topography.
π **Clip Abstract** Contact-based flexographic printing introduces fluid-splitting defects like viscous fingering, which cause nanometer-scale thickness variations in wet films. Sinovia manages these hydrodynamic instabilities by co-optimizing ink chemistry, plate properties, and anilox volumes to achieve flat layers.
#ViscousFingering, #FlexographicPrinting, #AniloxCylinders, #PrintedOLEDs, #PrintedElectronics, #RollToRollManufacturing