Journal Article

FZJ-2021-04873

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Phase-Field Simulation of Liquid–Vapor Equilibrium and Evaporation of Fluid Mixtures

Ronsin, O. J. J. (Corresponding author)FZJ* ; Jang, D. ; Egelhaaf, H.-J.FZJ* ; Brabec, C. J.FZJ* ; Harting, J. (Corresponding author)FZJ*

2021
Soc. Washington, DC

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Please use a persistent id in citations: http://hdl.handle.net/2128/33427  doi:10.1021/acsami.1c12079

Abstract: In solution processing of thin films, the material layer is deposited from a solution composed of several solutes and solvents. The final morphology and hence the properties of the film often depend on the time needed for the evaporation of the solvents. This is typically the case for organic photoactive or electronic layers. Therefore, it is important to be able to predict the evaporation kinetics of such mixtures. We propose here a new phase-field model for the simulation of evaporating fluid mixtures and simulate their evaporation kinetics. Similar to the Hertz–Knudsen theory, the local liquid–vapor (LV) equilibrium is assumed to be reached at the film surface and evaporation is driven by diffusion away from this gas layer. In the situation where the evaporation is purely driven by the LV equilibrium, the simulations match the behavior expected theoretically from the free energy: for evaporation of pure solvents, the evaporation rate is constant and proportional to the vapor pressure. For mixtures, the evaporation rate is in general strongly time-dependent because of the changing composition of the film. Nevertheless, for highly nonideal mixtures, such as poorly compatible fluids or polymer solutions, the evaporation rate becomes almost constant in the limit of low Biot numbers. The results of the simulation have been successfully compared to experiments on a polystyrene–toluene mixture. The model allows to take into account deformations of the liquid–vapor interface and, therefore, to simulate film roughness or dewetting.

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Contributing Institute(s):

1. Helmholtz-Institut Erlangen-Nürnberg Erneuerbare Energien (IEK-11)

Research Program(s):

1. 1215 - Simulations, Theory, Optics, and Analytics (STOA) (POF4-121) (POF4-121)
2. DFG project 449539983 - Prozess-Struktur Relationen für die lösungsmittelbasierte organische Photovoltaik (449539983)

Appears in the scientific report 2021

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Database coverage:
; ; Clarivate Analytics Master Journal List ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; IF >= 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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