Thickness-Dependent Dark-Bright Exciton Splitting and Phonon Bottleneck in CsPbBr<sub>3</sub>-Based Nanoplatelets Revealed via Magneto-Optical Spectroscopy.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36036573.
- Also identified by DOI 10.1021/acs.nanolett.2c01826 and PMC identifier 9479212.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The optimized exploitation of perovskite nanocrystals and nanoplatelets as highly efficient light sources requires a detailed understanding of the energy spacing within the exciton manifold. Dark exciton states are particularly relevant because they represent a channel that reduces radiative efficiency. Here, we apply large in-plane magnetic fields to brighten optically inactive states of CsPbBr<sub>3</sub>-based nanoplatelets for the first time. This approach allows us to access the dark states and directly determine the dark-bright splitting, which reaches 22 meV for the thinnest nanoplatelets. The splitting is significantly less for thicker nanoplatelets due to reduced exciton confinement. Additionally, the form of the magneto-PL spectrum suggests that dark and bright state populations are nonthermalized, which is indicative of a phonon bottleneck in the exciton relaxation process.