Computational investigation on the large energy gap between the triplet excited-states in acenes

Abstract

The large energy gap between the two triplet excited-states in acenes has a huge impact on their optical and electronic properties. Accurate calculation and full use of this gap have always been a major challenge in the field of organic semiconductor materials. In the present study, we focus on the precise description of the large gap between the T₁ and T₂ states, and taking a series of acenes (benzene, naphthalene, anthracene, tetracene, and pentacene) as examples, investigate their excited state behavior to verify the energy gap structure. The results show that the symmetry of the transition molecular orbital and the excited state properties have a great influence on the transition energy, and may be the main cause of the large energy gap.