Meena Rahul, Pandey Priya, Zuffa Caterina, Brázda Petr, Samolova Erika, McIntosh Nemo, Volpi Martina, Modesti Federico, Gatsios Christos, Turetta Nicholas, Catalano Luca, Choi Wookjin, Seki Shu, Cornil Jérôme, Erk Peter, Koch Norbert, Samorì Paolo, Maini Lucia, Schweicher Guillaume, Geerts Yves
Laboratory of Polymer Chemistry, Université Libre de Bruxelles (ULB), Boulevard du Triomphe, Bruxelles 1050, Belgium.
Dipartimento di Chimica "G. Ciamician", Via Selmi 2-Università di Bologna, Bologna I-40126, Italy.
Cryst Growth Des. 2025 Apr 23;25(9):3087-3099. doi: 10.1021/acs.cgd.5c00145. eCollection 2025 May 7.
The crystal structures of organic semiconductors are critical when they are integrated into optoelectronic devices, such as organic field-effect transistors (OFETs). In this study, we introduce a crystal engineering approach that leverages weak, nondirectional dispersion forces and steric effects, working together to govern the molecular packing. We investigated how the substitution at the peri-position affects the crystal structure in a series of oligorylene molecules. Upon elucidation of the crystal structures, we found a distinct difference between symmetrical and unsymmetrical derivatives. The unsymmetrical derivatives are prone to forming a sandwich herringbone (SHB) motif, while symmetrical derivatives exhibit a typical herringbone (HB) motif. In most of the rylene derivatives, substitutions at the peri-position triggered an "end-to-face" orientation within the HB structure, rather than an "edge-to-face" orientation, which occurs more often. Results from the Hirschfeld surface analysis provide evidence that the "end-to-face" orientation promotes C-H-π interactions between terminal methyl groups and the π-core of the molecules. While these C-H---π interactions contribute to the overall stability of the packing structure, they remain ineffective in enhancing the charge transport properties. In contrast, a particular derivative, tetramethyl perylene (), exhibits a HB structure with an edge-to-face orientation, promoting both C-H---π and π---π interactions. These interactions are crucial for improving the charge carrier mobility, as evidenced by mobility values. For , we could obtain the mobility value of 0.05 cm V s in OFETs, whereas a slightly higher mobility of 0.2 cm V s was observed with Field-Induced Time-Resolved Microwave conductivity (FI-TRMC) technique.
当有机半导体被集成到光电器件中，如有机场效应晶体管（OFET）时，其晶体结构至关重要。在本研究中，我们引入了一种晶体工程方法，该方法利用弱的、非定向的色散力和空间效应共同控制分子堆积。我们研究了在一系列低聚并苯分子中，周位取代如何影响晶体结构。在阐明晶体结构后，我们发现对称和不对称衍生物之间存在明显差异。不对称衍生物易于形成夹心人字形（SHB） motif，而对称衍生物表现出典型的人字形（HB） motif。在大多数并苯衍生物中，周位取代在HB结构内引发了“端对端”取向，而不是更常见的“边对端”取向。 Hirschfeld表面分析结果表明，“端对端”取向促进了末端甲基与分子π核之间的C-H-π相互作用。虽然这些C-H---π相互作用有助于堆积结构的整体稳定性，但它们在增强电荷传输性能方面仍然无效。相比之下，一种特殊的衍生物四甲基苝（）表现出具有边对端取向的HB结构，促进了C-H---π和π---π相互作用。这些相互作用对于提高电荷载流子迁移率至关重要，迁移率值证明了这一点。对于，我们在OFET中可以获得0.05 cm V s的迁移率值，而用场诱导时间分辨微波电导率（FI-TRMC）技术观察到略高的迁移率为0.2 cm V s。
