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) nanostructures, under an external electric field (𝐸𝑒𝑥𝑡 ) effects applied in z direction, are investigated using density functional theory (DFT) calculations. The Visualizer module of Material Studio software used to construct single-layer nanotube. Then, we use the CASTEP code for optimize and calculate the band structure, density of states and optical properties of carboxyl group substitution on Single-Walled Carbon Nanotube (SWCNT/Carboxyl). The 𝐸𝑒𝑥𝑡 effects lead to modulate the band gap and change the total density of states (TDOS), partial density of states (PDOS), absorption coefficient, dielectric function, optical conductivity, refractive index and loss function. The application of an 𝐸𝑒𝑥𝑡 effect on SWCNT/Carboxyl structure, lead to close its band gap. The peaks of TDOS around the fermi level are very weak. The absorption coefficient increases in visible range and decreases in ultraviolet (UV) domain, by reason of increased an 𝐸𝑒𝑥𝑡 effects. It is found that electronic structures and optical properties of SWCNT/Carboxyl, could be affected by the 𝐸𝑒𝑥𝑡 effects. All these results provide the important information for understanding and controlling the electronic and optical properties of 1D-crystals by an 𝐸𝑒𝑥𝑡 effects. This study can provide certain theoretical basis for our future experimental work of optoelectronic properties of SWCNT/Carboxyl material.