Accumulation and ordering of P3HT oligomers at the liquid–vapor interface with implications for thin-film morphology
Accumulation and ordering of P3HT oligomers at the liquid–vapor interface with implications for thin-film morphology
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P3HT 低聚物在液-汽界面的积累和排序对薄膜形态的影响
DOI：
10.1039/d3cp02718j
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发表时间：
2023
影响因子：
3.3
通讯作者：
Rossky, Peter J.
中科院分区：
文献类型：
--
作者：
Sowa, Jakub K.;Allen, Thomas C.;Rossky, Peter J.
已知半导体聚合物薄膜的形态对其光电性质具有深远的影响。虽然已经做出了相当大的努力来控制和理解影响这些系统的结构的过程，但在很大程度上仍然不清楚是什么物理因素决定了旋转浇铸膜中聚合物链的排列。在这里，我们调查的作用，聚（3-hexylthiophene）[P3 HT]的氯苯溶液中的液-气界面发挥的构象的几何形状所采用的聚合物。使用全原子分子动力学（MD），并支持玩具模型模拟，我们表明，随着浓度的增加，P3 HT低聚物在溶液中表现出强烈的倾向，为液-气界面。由于低聚物的主链和侧链的不同溶解度，在该界面附近，己基链和噻吩环相对于液体表面具有明显的取向偏好。在高浓度下，我们还建立了相当程度的低聚物间的对齐和噻吩环堆叠界面附近。我们的研究结果与现有的有限的实验证据，我们建议，界面结构可以作为一个模板的薄膜结构。我们认为，侧链和主链部分的溶剂亲和力的差异是界面附近的聚合物的各向异性取向的驱动力。这种更细粒度的描述与聚合物单元的通常整体表征形成对比。由于这种现象可以通过同时进行的化学设计和溶剂的选择来控制，因此这项工作建立了一种制造原理，这可能有助于开发更高功能的聚合物膜。
The morphology of semiconducting polymer thin films is known to have a profound effect on their opto-electronic properties. Although considerable efforts have been made to control and understand the processes which influence the structures of these systems, it remains largely unclear what physical factors determine the arrangement of polymer chains in spin-cast films. Here, we investigate the role that the liquid–vapor interfaces in chlorobenzene solutions of poly(3-hexylthiophene) [P3HT] play in the conformational geometries adopted by the polymers. Using all-atom molecular dynamics (MD), and supported by toy-model simulations, we demonstrate that, with increasing concentration, P3HT oligomers in solution exhibit a strong propensity for the liquid–vapor interface. Due to the differential solubility of the backbone and side chains of the oligomers, in the vicinity of this interface, hexyl chains and the thiophene rings, have a clear orientational preference with respect to the liquid surface. At high concentrations, we additionally establish a substantial degree of inter-oligomer alignment and thiophene ring stacking near the interface. Our results broadly concur with the limited existing experimental evidence and we suggest that the interfacial structure can act as a template for film structure. We argue that the differences in solvent affinity of the side chain and backbone moieties are the driving force for the anisotropic orientations of the polymers near the interface. This finer grained description contrasts with the usual monolithic characterization of polymer units. Since this phenomenon can be controlled by concurrent chemical design and the choice of solvents, this work establishes a fabrication principle which may be useful to develop more highly functional polymer films.