Redshift of excitons in carbon nanotubes caused by the environment polarizability

TL;DR

This paper investigates how the environment's polarizability causes redshifts in excitons within carbon nanotubes, revealing the dominant role of non-local polarizability effects and the influence of structural contact details.

Contribution

It provides a theoretical analysis using many-body perturbation theory to explain environmental effects on excitonic energies in carbon nanotubes, emphasizing the role of polarizability.

Findings

Redshifts are mainly due to the environment's polarizability.

Electronic coupling can enhance redshifts but is highly sensitive to contact structure.

Non-local polarizability effects are crucial in exciton energy modifications.

Abstract

Optical excitations of molecular systems can be modified by their physical environment. We analyze the underlying mechanisms within many-body perturbation theory, which is particularly suited to study non-local polarizability effects on the electronic structure. Here we focus on the example of a semiconducting carbon nanotube, which observes redshifts of its excitons when the tube is touched by another nanotube or other physisorbates. We show that the redshifts mostly result from the polarizability of the attached ad-system. Electronic coupling may enhance the redshifts, but depends very sensitively on the structural details of the contact.