Electronic states and optical properties of PbSe nanorods and nanowires

TL;DR

This paper presents a theoretical model for the electronic and optical properties of PbSe nanorods and nanowires, showing how dielectric contrast influences exciton binding and matching experimental absorption spectra.

Contribution

It introduces a four-band effective mass model for PbSe nanostructures and demonstrates its agreement with experimental size-dependent optical spectra.

Findings

Dielectric contrast enhances exciton binding in narrow nanostructures.

Self-interaction energies nearly cancel Coulomb binding, minimally affecting absorption spectra.

Theoretical predictions align well with experimental measurements.

Abstract

A theory of the electronic structure and excitonic absorption spectra of PbS and PbSe nanowires and nanorods in the framework of a four-band effective mass model is presented. Calculations conducted for PbSe show that dielectric contrast dramatically strengthens the exciton binding in narrow nanowires and nanorods. However, the self-interaction energies of the electron and hole nearly cancel the Coulomb binding, and as a result the optical absorption spectra are practically unaffected by the strong dielectric contrast between PbSe and the surrounding medium. Measurements of the size-dependent absorption spectra of colloidal PbSe nanorods are also presented. Using room-temperature energy-band parameters extracted from the optical spectra of spherical PbSe nanocrystals, the theory provides good quantitative agreement with the measured spectra.