First-principles study on electronic and optical properties of single-walled carbon nanotube under an external electric field

In this study, the electronic and optical properties of one-dimensional (1D) single-walled carbon nanotube (SWCNT) nano-structures, and under the external electric field (E-ext) applied in the z-direction, are investigated using density functional theory (DFT) calculations. The applied E-ext leads to significant modulation of the bandgap and changes the total density of states (TDOS), partial density of states (PDOS), absorption coefficient, dielectric function, optical conductivity, refractive index, and the loss function. The application of the E-ext on the SWCNT/Carboxyl structure leads to tighten its bandgap. The peaks of TDOS around the Fermi level are very weak. The absorption coefficient increases in visible range and decreases in ultraviolet (UV) domain proportionally with the E-ext. It is found that electronic structures and optical properties of the SWCNT/Carboxyl could be affected by the E-ext. All these results provide the important information for understanding and controlling the electronic and optical properties of 1D crystals by the E-ext. This study establishes a theoretical foundation for our future experimental work regarding optoelectronic properties of the SWCNT/Carboxyl material.