Exciton diffusion in semiconducting single-wall carbon nanotubes studied by transient absorption microscopy

TL;DR

This study investigates the spatiotemporal behavior of excitons in semiconducting single-wall carbon nanotubes using transient absorption microscopy, revealing exciton diffusion characteristics and decay dynamics.

Contribution

It provides direct measurements of exciton diffusion coefficients and decay times in isolated nanotubes using a novel microscopy approach.

Findings

Exciton diffusion coefficient of 200 cm²/s at room temperature.

Bi-exponential exciton decay with time constants of 0.66 ps and 2.8 ps.

Diffusion coefficients of 300 cm²/s at low temperatures (10 K and 150 K).

Abstract

Spatiotemporal dynamics of excitons in isolated semiconducting single-walled carbon nanotubes are studied using transient absorption microscopy. Differential reflection and transmission of an 810-nm probe pulse after excitation by a 750-nm pump pulse are measured. We observe a bi-exponentially decaying signal with a fast time constant of 0.66 ps and a slower time constant of 2.8 ps. Both constants are independent of the pump fluence. By spatially and temporally resolving the differential reflection, we are able to observe a diffusion of excitons, and measure a diffusion coefficient of 200 cm2/s at room temperature and 300 cm2/s at lower temperatures of 10 K and 150 K.