All‐atom molecular dynamics simulations are performed to investigate the structural and conformational properties of a regioregular poly(3‐hexylthiophene) (P3HT) crystal in the presence of a gold (Au) substrate terminated with an n‐alkanethiol self‐assembled monolayer (SAM). The employed orientation of the P3HT crystals deposited on the SAM is the edge‐on, since this orientation is believed to be the most energetically favorable and stable, also yielding the highest charge carrier mobility in organic thin‐film transistors. The unit cell of the overall Au/SAM interfacial layer is obtained through detailed ab initio calculations. Systems with a varying number of P3HT stacks on the Au/SAM substrate are studied with an all‐atom force field in order to elucidate the effect of polymer thickness on the structural properties of the system. All final structures are found to be stable and well‐equilibrated. Insights into the P3HT crystal structure are provided for the P3HT layers in direct contact with the SAM, but also for those deeper in the polymer film. According to the simulations, the majority of conformational and packing properties of the P3HT film are practically similar to those of the bulk crystalline P3HT material, implying that its structure remains unaffected by the presence of the underlying Au/SAM substrate.

中文翻译：

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沉积在金上的烷硫醇自组装单分子膜上吸附的结晶P3HT膜的结构和构型

进行全原子分子动力学模拟以研究在以正烷硫醇自组装单层（SAM）终止的金（Au）底物存在下区域规则的聚（3-己基噻吩）（P3HT）晶体的结构和构象性质）。沉积在SAM上的P3HT晶体采用的取向是沿边的，因为这种取向被认为是能量上最有利和最稳定的，并且在有机薄膜晶体管中也产生了最高的载流子迁移率。通过详细的从头算来获得整个Au / SAM界面层的晶胞。为了研究聚合物厚度对系统结构性能的影响，研究了在全原子力场下在Au / SAM基板上具有不同数量P3HT堆叠的系统。发现所有最终结构均稳定且平衡良好。对于与SAM直接接触的P3HT层，以及对聚合物薄膜较深的层，都提供了对P3HT晶体结构的了解。根据模拟，P3HT膜的大多数构象和堆积特性实际上与块状晶体P3HT材料相似，这表明其结构不受下面的Au / SAM基板的影响。