Optical orientation and alignment of excitons in ensembles of inorganic perovskite nanocrystals

TL;DR

This study investigates the optical orientation and alignment of excitons in CsPbI3 perovskite nanocrystals, revealing anisotropic exchange splitting influenced by nanocrystal shape, with potential implications for optoelectronic applications.

Contribution

It provides the first measurement of exciton anisotropic exchange splitting in inorganic perovskite nanocrystals and links it to nanocrystal shape anisotropy.

Findings

Average anisotropic splitting of 120 μeV at 2K

Shape anisotropy significantly contributes to exciton splitting

Optical orientation and alignment of excitons demonstrated

Abstract

We demonstrate the optical orientation and alignment of excitons in a two-dimensional layer of CsPbI$_3$ perovskite nanocrystals prepared by colloidal synthesis and measure the anisotropic exchange splitting of exciton levels in the nanocrystals. From the experimental data at low temperature (2K), we obtain the average value of anisotropic splitting of bright exciton states of the order of 120{\mu}eV. Our calculations demonstrate that there is a significant contribution to the splitting due to the nanocrystal shape anisotropy for all inorganic perovskite nanocrystrals.