Luminescence Properties of Individual Empty and Water-filled Single-Walled Carbon Nanotubes

TL;DR

This study investigates how water filling affects the photoluminescence properties of single-walled carbon nanotubes, revealing shifts in spectra, differences in line widths, and exciton-phonon interactions through spectroscopy and modeling.

Contribution

It provides the first detailed comparison of PL properties between empty and water-filled SWCNTs, including spectral shifts and exciton-phonon coupling insights.

Findings

Water filling causes red-shifts in PL spectra for multiple chiralities.

Empty nanotubes exhibit narrower emission lines and less broadening.

Water filling influences the radiative lifetime of excitons.

Abstract

The influence of water-filling on the photoluminescence (PL) properties of SWCNTs is studied by ensemble and single-molecule PL spectroscopy. Red-shifted PL and PL excitation spectra are observed upon water filling for 16 chiralities and can be used to unambiguously distinguish empty SWCNTs from filled ones. The effect of water-filling on the optical transitions is well reproduced by a continuum dielectric constant model previously developed to describe the influence of the nanotube outer environment. Empty nanotubes display narrower luminescence lines and lower inhomogeneous broadening, signatures of reduced extrinsic perturbations. The radial breathing mode (RBM) phonon side band is clearly observed in the PL spectrum of small diameter empty tubes and a strong exciton-phonon coupling is measured for this vibration. Biexponential PL decays are observed for empty and water filled tubes, and only the short living component is influenced by the water-filling. This may be attributed to a shortening of the radiative lifetime of the bright state by the inner dielectric environment.