Structure Dependence of Photoluminescence Solvatochromic Energy Shifts Based on Exciton Localization in Locally Functionalized Single-Walled Carbon Nanotubes

• Published in: Journal of physical chemistry. C 2021-06, Vol.125 (23), p.12758-12766
• Main Authors: Niidome, Yoshiaki, Yu, Boda, Juhasz, Gergely, Fujigaya, Tsuyohiko, Shiraki, Tomohiro
• Format: Article
• Language: English
• Subjects: C: Spectroscopy and Dynamics of Nano, Hybrid, and Low-Dimensional Materials
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.1c02109

Defect doping of single-walled carbon nanotubes (SWCNTs) by local chemical functionalization produces locally functionalized SWCNTs (lf-SWCNTs) that emit red-shifted and bright photoluminescence (PL) in near-infrared regions beyond 1000 nm (E 11 * PL) from localized excitons trapped at doped sites in the tubes. In this study, we use lf-SWCNTs with different doped sites such as proximal aryl-doped sites and oxygen-doped sites (ether-type and epoxide-type) showing largely red-shifted PL than typical E 11 * PL, which allow us to elucidate the structural effects on PL solvatochromism (via organic solvent injection) and reveal the excitonic property variations of the localized excitons. We correlate PL solvatochromic energy shifts of the lf-SWCNTs with solvent orientation polarization parameters. The proximal aryl-doped sites of bisaryl-modified lf-SWCNTs emit E 11 2* PL (∼1253 nm), and the observed solvatochromic energy shifts appeared between those of the E 11 PL (∼980 nm) and E 11 * PL (∼1125 nm). The epoxide-type doped sites of the oxygen-doped lf-SWCNTs emit E 11 *b PL (∼1250 nm), with almost no solvatochromism; this was totally different from the trends seen for other PL, including E 11 *a PL from the ether-type doped sites. The unique structure-dependent solvatochromism is correlated with the (1) localization-induced polarizability or dipole moment changes and (2) different degrees of exciton localization at doped sites.