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

Abstract

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···S hydrogen bonds, which are thought to stabilize the molecules in crystal environments. Furthermore, the syn-TAS-ADTs show more serious nonlocal electron–phonon interactions than the anti-TAS-ADTs, which could be ascribed to the larger S···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···π interaction, the balance relationship between electrostatic, induction, dispersion, and exchange repulsion interactions, and the C–H···S hydrogen bonds are responsible for the very different crystal packing motifs between these materials.