Theoretical Investigations on Molecular Packing Motifs and Charge Transport Properties of a Family of Trialkylsilylethynyl-Modified Pentacenes/Anthradithiophenes

A family of trialkylsilylethynyl (TAS)-functionalized pentacenes (PENs) and anthradithiophenes (ADTs) are of immense interest due to their good solubility and air stability for uses in optoelectronic devices. Different TAS-substituted PENs and ADTs would result in different crystal packing motifs and carrier transport properties. Quantum nuclear-enabled hopping model combined with molecular dynamics (MD) simulations was used to investigate the effects of the chemical modifications on the carrier transport properties. The disorder-free hole mobilities show that 6,13-bis(trialkylsilylethynyl)anthradithiophenes (TAS-ADTs) own better intrinsic hole transport behaviors than 6,13-bis(trialkylsilylethynyl)pentacenes (TAS-PENs). The MD simulations show that in comparison with TAS-PENs, the thermal disorder effects are less significant for TAS-ADTs; this is probably due to the C-H center dot center dot center dot S hydrogen bonds, which are thought to stabilize the molecules in crystal environments. Furthermore, the syn-TASADTs show more serious nonlocal electron-phonon interactions than the anti-TAS-ADTs, which could be ascribed to the larger S center dot center dot center dot S overlap between neighboring molecules in the syn-TAS-ADTs. Additionally, symmetry-adapted perturbation theory and Hirshfeld surface analyses were performed to characterize the effects of noncovalent interactions on packing motifs. The results indicate that the C-H-center dot center dot center dot pi interaction, the balance relationship between electrostatic, induction, dispersion, and exchange repulsion interactions, and the C-H center dot center dot center dot S hydrogen bonds are responsible for the very different crystal packing motifs between these materials.