Strong reduction of exciton-phonon coupling in high crystalline quality single-wall carbon nanotubes: a new insight into broadening mechanisms and exciton localization

TL;DR

This study demonstrates that high crystalline quality single-wall carbon nanotubes exhibit significantly narrower photoluminescence linewidths at low temperatures due to reduced exciton-phonon coupling and localization, providing new insights into dephasing mechanisms.

Contribution

It reveals that intrinsic crystalline quality reduces exciton localization and phonon coupling, leading to narrower emission lines in high-quality SWNTs, advancing understanding of their optical properties.

Findings

Linewidths an order of magnitude narrower than typical samples

Reduced exciton-phonon coupling in high-quality SWNTs

Exciton localization influenced by crystalline quality

Abstract

Carbon nanotubes are quantum sources whose emission can be tuned at telecommunication wavelengths by choosing the diameter appropriately. Most applications require the smallest possible linewidth. Therefore, the study of the underlying dephasing mechanisms is of utmost interest. Here, we report on the low-temperature photoluminescence of high crystalline quality individual single-wall carbon nanotubes synthesized by laser ablation (L-SWNTs) and emitting at telecommunication wavelengths. A thorough statistical analysis of their emission spectra reveals a typical linewidth one order of magnitude narrower than that of most samples reported in the literature. The narrowing of the PL line of L-SWNTs is due to a weaker effective exciton-phonon coupling subsequent to a weaker localization of the exciton. These results suggest that exciton localization in SWNTs not only arises from interfacial effects, but that the intrinsic crystalline quality of the SWNT plays an important role.