Theoretical investigation of the substitution effects on carrier transport properties of tetrathia[22]annulene-[2,1,2,1] derivatives

Abstract

The charge transport properties of tetrathia[22]annulene-[2,1,2,1] derivatives (DPTTA, $$\hbox {DPTTACH}_{3}$$ and DPTTACl) were investigated by the density functional theory coupled with incoherent charge-hopping model at the molecular and crystal levels to shed light on the relationship between the charger carrier mobility and substitution effects. It is found that that the low-lying and delocalized LUMOs and larger adiabatic electron affinities of these compounds are beneficial to their stability when acting as n-type organic semiconductors. The reorganization energy and transfer integral can significantly influence the charge carrier mobility. The $$\hbox {DPTTACH}_{3}$$ has large electron mobility ( $$0.177\hbox { cm}^{2}\cdot \hbox { V}^{-1}\cdot \hbox { s}^{-1}$$ ) owing to the small reorganization energy and larger transfer integral originating from the face-to-face $$\uppi $$ – $$\uppi $$ stacking among the three compounds. From the viewpoint of transfer integral, the transfer integral among the dominant hopping pathways indicates that the charge transport occurs in the parallel dimers with $$\uppi $$ – $$\uppi $$ interaction. On the basis of the angular resolution anisotropic mobility investigation, the $$\hbox {DPTTACH}_{3}$$ exhibit remarkable anisotropic behavior. We hope that our work can help the experimenters understand how to tune charge transport through a small molecular modification.