Design of novel tetra-hetero[8]circulenes: a theoretical study of electronic structure and charge transport characteristics

Abstract

In the present work, a series of new tetra-hetero[8]circulenes were theoretically designed in which heteroatoms include O, S, Se and N. Their electronic structure and characteristics of charge transport were investigated using DFT based computational methods. Except for the compounds containing Se-atoms (3a and 3b), all remaining compounds exhibit planar and highly symmetrical structures featuring novel aromatic features: the inner eight-membered ring is anti-aromatic and the outer fused rings are aromatic. The predicted UV spectrum and reduction potential of 1a agree well with available experimental values. Following replacement of H-atoms by F-atoms, the energy levels of the frontier orbitals of 1b–4b are consistently decreased as compared to those of 1a–4a. Based on the calculated properties of electrochemistry and charge transport, the molecules 1a–4a and 4b are suggested to be good candidates for p-type semiconductors. More importantly, the molecules 1b–3b are revealed to be potential ambipolar organic semiconductors.