First-passage theory of exciton population loss in single-walled carbon nanotubes reveals micron-scale intrinsic diffusion lengths

TL;DR

This study uses a first-passage model to analyze exciton dynamics in single-walled carbon nanotubes, revealing intrinsic diffusion lengths of up to several micrometers in pristine samples, which are much longer than previously observed.

Contribution

The paper introduces a first-passage theoretical approach to accurately extract intrinsic exciton properties in SWCNTs from experimental data, accounting for environmental effects.

Findings

Intrinsic diffusion lengths of 1.3-4.7 micrometers in pristine SWCNTs.

Intrinsic exciton lifetimes of 350-750 ps.

High absorption cross-sections of 2.1-3.6 x 10^-17 cm^2/atom.

Abstract

One-dimensional crystals have long range translational invariance which manifests as long exciton diffusion lengths, but such intrinsic properties are often obscured by environmental perturbations. We use a first-passage approach to model single-walled carbon nanotube (SWCNT) exciton dynamics (including exciton-exciton annihilation and end effects) and compare it to results from both continuous-wave and multi-pulse ultrafast excitation experiments to extract intrinsic SWCNT properties. Excitons in suspended SWCNTs experience macroscopic diffusion lengths, on the order of the SWCNT length, (1.3-4.7 um) in sharp contrast to encapsulated samples. For these pristine samples, our model reveals intrinsic lifetimes (350-750 ps), diffusion constants (130-350 cm^2/s), and absorption cross-sections (2.1-3.6 X 10^-17 cm^2/atom) among the highest previously reported.and diffusion lengths for SWCNTs.