Diameter-Dependent Photoluminescence Properties in Color Centers of Air-Suspended Single-Walled Carbon Nanotubes*

Color centers in single-walled carbon nanotubes are of interest because of their single-photon emission at room temperature in the telecom range, but the lack of vapor-phase reaction route for forming the color centers hinders the use of the excellent optical properties of air-suspended carbon nanotubes. We herein demonstrate the functionalization of air-suspended carbon nanotubes using iodobenzene as a precursor. We rationally design the chemical reaction procedure without compromising the suspended structure. Formed phenyl group serves as a color center and exhibits localized exciton emission peaks E₁₁^* and E₁₁^*- in addition to the free exciton emission peak E₁₁. We characterize representative 12 chiralities to reveal the diameter-dependent reactivity and optical property of the color centers. We quantitatively describe the reactivity, where a strain of nanotube curvature promotes the reaction. The trapping potential of E₁₁^* and E₁₁^*- excitons also shows the diameter dependence, which we discuss in the presentation.