Theoretical study on the regulation of molecular stacking and charge transport properties of Nitrogen-heteroacene derivatives containing benzocyclobutadiene

Abstract

The precise control of molecular packing patterns in solid-state materials is crucial for determining their charge transport properties. This study systematically investigates the molecular packing patterns and charge transport properties of triisopropylsilylacetylene (TIPS)-benzobenzene molecules functionalized with different molecular lengths using benzocyclobutadiene (BCBD) as a linker to connect polycyclic aromatic hydrocarbons. In the solid state, these molecules exhibited both herringbone stacking and 1D/2D π-stacking. We discovered an intrinsic relationship between the stacking motifs and the position of the TIPS in the investigated systems. Depending on the ratio (R) of skeleton lengths at both ends of the main chain with TIPS as the split point in the different ranges of ∼2.0, 2.0–3.0, and 3.0∼, these crystals exhibited different packing patterns. Meanwhile, the R value is closely related to the anisotropy of mobility of these organic semiconductors. Multi-scale calculations, including density functional theory (DFT) and molecular dynamics (MD) simulations, were employed to examine the impact of incorporating the BCBD structural moiety on charge transport properties. The results demonstrate that BCBD effectively extends the LUMO orbitals and maintains a balance between hole and electron transport properties. This work aims to elucidate the experimental phenomena and establish a theoretical foundation for the development of high-mobility semiconductor materials.