Theoretical study on the electronic structures and photophysical properties of carbon nanorings and their analogues

Abstract

Density functional theory (DFT) is used in a series of hexacene nanoring ([6]CA), its boron nitride analogue ([6]CA-BN) and lithium ion doping derivatives to obtain an insight into electronic structure, aromaticity property, energy gap, ionization potential, electron affinity and reorganization energy. DFT calculations of these nanorings indicate that the energy gaps of the carbon nanorings are smaller than those of the boron nitride nanorings. The lithium ion doping will remarkably reduce the HOMO and LUMO energy. The aromaticities of the rings are investigated though nucleus-independent chemical shift (NICS) values. The NICS scan suggests that the aromaticities of carbon nanoring systems are more than those of boron nitride analogues, the aromaticities of boron nitride compounds are very weak due to orbital localization. We also calculate the reorganization energy to investigate the charge transport properties. The results show that the carbon nanoring and their analogues could serve as bipolar carrier transport materials in photoelectric functional materials, and the lithium ion doping significantly improves the charge transport properties. The [6]CA-BN nanorings serve as better electron-transport materials. Furthermore, the lithium ion doping significantly affects the charge transfer property of [6]CA-BN nanoring, making it used as bipolar carrier transport materials. The time dependant DFT investigations show that the boron nitride substitution leads to an important change in absorption spectrum with blue-shift. And lithium ion doping has no obvious influence on absorption spectrum.