Exciton fine structure in CdSe nanoplatelets using a quasi-2D screened configuration-interaction framework

TL;DR

This paper presents a theoretical framework combining DFT, screened configuration interaction, and a quasi-2D dielectric model to accurately compute exciton fine-structure splittings in CdSe nanoplatelets with different crystal structures.

Contribution

The authors develop a transferable, efficient computational method for exciton calculations in quasi-2D nanomaterials, incorporating atomistic details and anisotropic dielectric screening.

Findings

Wurtzite structures show the largest bright-bright splitting.

Zincblende structures exhibit smaller splittings due to symmetry breaking.

The methodology accurately captures exciton properties with low computational cost.

Abstract

We compute exciton binding energies and fine-structure splittings in CdSe nanoplatelets with two zincblende geometries and one wurtzite geometry, finding that the wurtzite structure exhibits the largest bright-bright splitting due to its intrinsic in-plane anisotropy, while the zincblende structures show smaller but finite splittings arising from atomistic symmetry breaking at edges and corners. These results are obtained using a theoretical framework that we developed, which combines DFT single-particle states with screened configuration interaction, a quasi-2D dielectric screening model, and an efficient Coulomb-cutoff scheme that eliminates periodic-image interactions and enables accurate Coulomb and exchange integrals at low computational cost. This methodology provides a transferable and practical route for studying excitons in CdSe nanoplatelets and other quasi-two-dimensional nanomaterials.