Effect of co-doping on dielectric function spectra and static refractive indices of single-walled carbon nanotubes: A first principles study

This paper details a density functional theory (DFT) based ab initio study on the effect of co-doping on the dielectric function spectra and refractive indices of single-walled carbon nanotubes (SWCNTs). Dielectric function spectra of a pristine (8,0) SWCNT; (8,0) SWCNT co-doped with aluminum (Al) and phosphorus (P); (8,0) SWCNT co-doped with Al, P, and nitrogen (N); (9,0) SWCNT doped with Al; and (9,0) SWCNT co-doped with Al and boron (B) have been calculated using DFT-based Cambridge sequential total energy package (CASTEP) code. Polarized and unpolarized light as well as light through polycrystalline media have been considered. Analysis involves calculation and comparison of static refractive indices of the pristine and co-doped SWCNTs. Co-doping with Al and P results in a substantial increase in the value of the static refractive index while co-doping of Al, N, and P results in a reduction in the value of static refractive index though it does not fall lower than that of the pristine SWCNT. Thus, it can be concluded that co-doping with atoms of different combinations of elements can be evolved as a novel and effective tool for tuning the dielectric function and static refractive index values of SWCNTs. It will prove to be highly significant for effective designing of various sensitive optical devices using SWCNTs.