Simulation of Crystal Nuclei at the Liquid-Air Interface toward Morphology Control via Surface Tension

SF Ke and BY Peng and RH Wu and J Ren and YJ Zhao and QY Sheng and HY Li, JOURNAL OF PHYSICAL CHEMISTRY C, 127, 17231-17238 (2023).

DOI: 10.1021/acs.jpcc.3c04247

Surfacetension is a crucial factor in the crystallization of organicsemiconductors from solutions. However, the current conclusions basedon experimental results have been primarily empirical and qualitative,making it hard to distinguish the role of surface tension from othersolvent properties. In this study, we employed both molecular dynamicssimulations and experiments to investigate crystal nuclei behaviorat the liquid-air interface. Through equilibrium simulations and freeenergy calculations, we quantitatively described the moving behaviorof nuclei in various solvents, relating it to an interfacial transition,in terms of interfacial tension. Nuclei tend to remain at the liquid-airinterface if the surface tension of solvents is higher than the surfacefree energy of nuclei but sink into the bulk liquid otherwise. Furthermore,aside from governing the nuclei behavior, surface tension also determinesthe crystallization location, as confirmed through growing crystalson substrates with Ag nanowires as impediments. By clarifying therole of surface tension, our research contributes to the knowledgeof solution crystallization of organic semiconductors and the establishmentof a framework for tuning processing conditions and crystal morphologyfor future studies.

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