Bright-exciton fine structures splittings in single perovskite nanocrystals

TL;DR

This study reveals that single perovskite CsPbI3 nanocrystals exhibit large bright-exciton fine structure splittings, which can be manipulated by photo-charging, offering new insights into exciton dynamics and potential quantum applications.

Contribution

It demonstrates the presence of large bright-exciton FSS in single perovskite nanocrystals and shows how photo-charging can control this splitting, advancing understanding of exciton behavior in these materials.

Findings

Bright-exciton FSS as large as hundreds of μeV detected.

Photo-charging eliminates electron-hole exchange interaction.

PL doublet can switch to a single peak upon charging.

Abstract

Although both epitaxial quantum dots (QDs) and colloidal nanocrystals (NCs) are quantum-confined semiconductor nanostructures, so far they have demonstrated dramatically-different exciton fine structure splittings (FSSs) at the cryogenic temperature. The single-QD photoluminescence (PL) is dominated by the bright-exciton FSS, while it is the energy separation between bright and dark excitons that is often referred to as the FSS in a single NC. Here we show that, in single perovskite CsPbI3 NCs synthesized from a colloidal approach, a bright-exciton FSS as large as hundreds of {\mu}eV can be resolved with two orthogonally- and linearly-polarized PL peaks. This PL doublet could switch to a single peak when a single CsPbI3 NC is photo-charged to eliminate the electron-hole exchange interaction. The above findings have prepared an efficient platform suitable for probing exciton and spin dynamics of semiconductor nanostructures at the visible-wavelength range, from which a variety of practical applications such as in entangled photon-pair source and quantum information processing can be envisioned.