Analysis of the oscillatory wetting–dewetting motion of a volatile drop during the deposition of polymer on a solid substrate

Zigelman, Anna; Jabal, Mohammad Abo; Manor, Ofer

doi:10.1039/c9sm00192a

Cited by 7 publications

(4 citation statements)

References 35 publications

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“…Recently, Jabal et al observed a wetting−dewetting transition caused by the variation in surface tension near the CL as a result of the solute concentration. 52,53 This is in accordance with the above arguments.…”

Section: ■ Results and Discussionsupporting

confidence: 91%

Drying Droplets with Soluble Surfactants

Man

et al. 2019

Langmuir

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We propose a theory for the drying of liquid droplets of surfactant solutions. We show that the added surfactant hinders droplet receding and facilitates droplet spreading, causing a complex behavior of the contact line of an evaporating droplet: the contact line first recedes, then advances, and finally recedes again. We also show that the surfactant can change the deposition pattern from mountainlike to volcano-like and then to coffee-ring-like. Specially, when the contact line motion undergoes a clear receding− advancing transition, a two-ring pattern is formed. The mechanism of the two-ring formation is different from the stick−slip mechanism proposed previously and may be tested experimentally.

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Section: ■ Results and Discussionsupporting

confidence: 91%

Drying Droplets with Soluble Surfactants

Man

et al. 2019

Langmuir

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“…When the substrate was heated, fluid flowed outward the droplet due to high solvent evaporation rates at the edges. [30][31][32][33] In other words, the capillary flow carried the QDs to the droplet edge (Figure 2a(ii)), result-ing in an increased QD concentration at the droplet edge. As the heating process prolonged, more solvent was evaporated, resulting in the reduction of the contact angle between the droplet and the substrate as shown in Figure 2b-e.…”

Section: Resultsmentioning

confidence: 99%

High‐Resolution, Highly Transparent, and Efficient Quantum Dot Light‐Emitting Diodes

et al. 2023

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Aiming at next‐generation displays, high‐resolution quantum dot light‐emitting diodes (QLEDs) with high efficiency and transparency are highly desired. However, there is limited study involving the improvements of QLED pixel resolution, efficiency, and transparency simultaneously, which undoubtedly restricts the practical applications of QLED for next‐generation displays. Here, the strategy of electrostatic force‐induced deposition (EF‐ID) is proposed by introducing alternating polyethyleneimine (PEI) and fluorosilane patterns to synergistically improve the pixel accuracy and transmittance of QD patterns. More importantly, the leakage current induced by the void spaces between pixels that is usually reported for high‐resolution QLEDs is greatly suppressed by substrate‐assisted insulating fluorosilane patterns. Finally, high‐performance QLEDs with high resolution ranging from 1104 to 3031 pixels per inch (PPI) and a high efficiency of 15.6% are achieved, among the best performances of high resolution QLEDs. Notably, the high resolution QD pixels greatly enhance the transmittance of the QD patterns, thus prompting an impressive transmittance of 90.7% for the transparent QLEDs (2116 PPI), which represents the highest transmittance of transparent QLED devices. Consequently, this work contributes an effective and general approach for high‐resolution QLEDs with high efficiency and transparency.

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“…where φ(r, t) is the particle volume fraction averaged by the film thickness, ρ l is the liquid density, and U ω is the fluid flow velocity in subdomain ω. The vapor flux density J(r, t) is determined using the Hertz-Knudsen formula [35,36,37,38,39,40]…”

Section: Model Equationsmentioning

confidence: 99%

Nonuniform heating of a substrate in evaporative lithography

Al-Muzaiqer,

Kolegov,

Ivanova

et al. 2021

Preprint

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The work is devoted to the study of one method connected with structured sediments formation, which belongs to the direction of evaporative lithography. A series of experiments were carried out with nonuniform evaporation of an isopropanol film containing polystyrene microspheres that occurred in an open cylindrical cell. The local inhomogeneity of the vapor flux density was achieved due to the temperature gradient. A copper rod was mounted in the central part of the bottom of the cell for further heating. The thermocapillary flow resulting from the surface tension gradient due to the temperature drop transfers the particles that were originally at rest along the bottom of the cell. The effect of the initial thickness of the liquid layer on the height and area of the sediment (cluster) formed in the central region of the cell is experimentally studied. The velocity of the particles was measured using particle image velocimetry. A mathematical model describing the process at the initial stage is developed. The equations of heat transfer and thermal conductivity were used to define the temperature distribution in the liquid and the cell. The fluid flow was simulated by the lubrication approximation. The particle distribution was modeled using the convection-diffusion equation. The evaporation flux density was calculated using the Hertz-Knudsen equation. The dependence of the liquid viscosity on the particle concentration was described by Mooney's formula. Numerical results showed that the liquid film gradually becomes thinner in the central region, as the surface tension decreases with increasing temperature. The liquid flow is directed to the heater near the substrate. It transfers the particles to the center of the cell. The volume fraction of the particles increases over time in this region. The work done allowed us to formulate the conclusion that the heat flow from the heater affects the geometry of the sediment for two reasons. First, the Marangoni flow velocity depends on the temperature gradient. Secondly, the decrease in film thickness near the heater depends on the temperature.

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Analysis of the oscillatory wetting–dewetting motion of a volatile drop during the deposition of polymer on a solid substrate

Abstract: We employ a theoretical model to explain the wetting–dewetting motion of the contact line by incorporating opposing evaporation and Marangoni induced flows in the deposition process.

Cited by 7 publications

References 35 publications

Drying Droplets with Soluble Surfactants

Drying Droplets with Soluble Surfactants

High‐Resolution, Highly Transparent, and Efficient Quantum Dot Light‐Emitting Diodes

Nonuniform heating of a substrate in evaporative lithography

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