Many-particle excitations in non-covalently doped single-walled carbon nanotubes

• Published in: Scientific reports Vol. 9; no. 1; pp. 14985 - 8
• Main Authors: Eremin, Timofei V., Obraztsov, Petr A., Velikanov, Vladimir A., Shubina, Tatiana V., Obraztsova, Elena D.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18-10-2019; Nature Publishing Group
• Subjects: 639/301/357/73; 639/624/399/73; Absorption; Carbon; Energy; Humanities and Social Sciences; Hydrochloric acid; Kinetics; multidisciplinary; Nanotechnology; Nanotubes; Photons; Science; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-50333-7

Doping of single-walled carbon nanotubes leads to the formation of new energy levels which are able to participate in optical processes. Here, we investigate (6,5)-single walled carbon nanotubes doped in a solution of hydrochloric acid using optical absorption, photoluminescence, and pump-probe transient absorption techniques. We find that, beyond a certain level of doping, the optical spectra of such nanotubes exhibit the spectral features related to two doping-induced levels, which we assign to a localized exciton
X
and a trion
T
, appearing in addition to an ordinary exciton
E
1
. We evaluate the formation and relaxation kinetics of respective states and demonstrate that the kinetics difference between
E
1
and
X
energy levels perfectly matches the kinetics of the state
T
. This original finding evidences the formation of trions through nonradiative relaxation via the
X
level, rather than via a direct optical excitation from the ground energy state of nanotubes.