Topological Defects in Semiconducting Carbon Nanotubes as Triplet Exciton Traps and Single-Photon Emitters

TL;DR

This study reveals that topological defects in semiconducting carbon nanotubes can trap triplet excitons and serve as single-photon emitters, with potential applications in quantum light sources and optoelectronics.

Contribution

It identifies the helical Stone-Wales defect as a key trap for triplet excitons and characterizes its properties relevant for single-photon emission in nanotubes.

Findings

Helical Stone-Wales defect traps triplet excitons.

Zero-phonon line predicted at 1.6 μm within telecom range.

Weak electron-phonon coupling suggests efficient single-photon emission.

Abstract

We investigate the role of topological defects in exciton behavior in (6,5) semiconducting single-walled carbon nanotubes using density functional theory. Our study identifies the helical Stone-Wales defect as a prominent trap for triplet excitons, characterized by a large zero-field splitting consistent with experimental data and a small singlet-triplet gap. The weak electron-phonon coupling, as evidenced by a Huang-Rhys factor of 0.74, renders it a promising single-photon emitter, with the zero-phonon line predicted at 1.6 $\mu$m, within the telecom range. These insights into defect-engineered electronic structure and exciton dynamics offer promising opportunities for improving the performance of carbon nanotube-based quantum light sources and optoelectronic devices.