Biexciton generation rates in CdSe nanorods are length independent

TL;DR

This study investigates how the shape of CdSe nanorods influences multiexciton generation rates, revealing that these rates are surprisingly independent of the nanorod aspect ratio due to distinct scaling behaviors.

Contribution

It introduces an atomistic semiempirical pseudopotential model combined with a stochastic approach to analyze MEG in nanorods of various shapes and sizes.

Findings

MEG rates are roughly independent of nanorod aspect ratio.

Scaling of trion state density and Coulomb couplings differ from spherical nanocrystals.

Multiexciton generation is influenced more by diameter than aspect ratio.

Abstract

We study how shape affects multiexciton generation (MEG) rates in a semiconducting nanocrystal by considering CdSe nanorods with varying diameters and aspect ratios. The calculations employ an atomistic semiempirical pseudopotential model combined with an efficacious stochastic approach applied to systems containing up to 20,000 atoms. The effect of nanorod diameter and aspect ratio on multiexciton generation rates is analyzed in terms of the scaling of the density of trion states and the scaling of the Coulomb couplings. Both show distinct scaling from spherical nanocrystals leading to a surprising result where the multiexciton generation rates are roughly independent of the nanorod aspect ratio