The substitution of heteroatoms and the functionalisation of molecules are established strategies in chemical synthesis. They target the precise tuning of the electronic properties of hydrocarbon molecules to improve their performance in various applications and increase their versatility. Modifications to the molecular structure often lead to simultaneous changes in the morphology such as different crystal structures. These changes can have a stronger and unpredictable impact on the targeted property. The complex relationships between substitution/functionalization in chemical synthesis and the resulting modifications of properties in thin films or crystals are difficult to predict and remain elusive. Here we address these effects for charge carrier transport in organic crystals by combining simulations of carrier mobilities with crystal structure prediction based on density functional theory and density functional tight binding theory. This enables the prediction of carrier mobilities based solely on the molecular structure and allows for the investigation of chemical modifications prior to synthesis and characterisation. Studying nine specific molecules with tetracene and rubrene as reference compounds along with their combined modifications of the molecular cores and additional functionalisations, we unveil systematic trends for the carrier mobilities of their polymorphs. The positive effect of phenyl groups that is responsible for the marked differences between tetracene and rubrene can be transferred to other small molecules such as NDT and NBT leading to a mobility increase by large factors of about five.

杂原子的取代和分子的功能化是化学合成中的既定策略。他们的目标是精确调节碳氢化合物分子的电子特性，以提高其在各种应用中的性能并增加其多功能性。分子结构的修饰通常会导致形态的同时变化，例如不同的晶体结构。这些变化可能会对目标财产产生更强烈且不可预测的影响。化学合成中的取代/官能化与由此产生的薄膜或晶体性质改变之间的复杂关系很难预测并且仍然难以捉摸。在这里，我们通过将载流子迁移率模拟与基于密度泛函理论和密度泛函紧束缚理论的晶体结构预测相结合来解决有机晶体中载流子传输的这些影响。这使得能够仅根据分子结构预测载流子迁移率，并允许在合成和表征之前研究化学修饰。研究以并四苯和红荧烯作为参考化合物的九种特定分子以及它们对分子核心的组合修饰和附加功能化，揭示了它们多晶型物的载流子迁移率的系统趋势。造成并四苯和红荧烯之间显着差异的苯基的积极作用可以转移到其他小分子，例如 NDT 和 NBT，从而导致迁移率增加约五倍。