Direct Observation of the Exciton-Polaron in Single CsPbBr<sub>3</sub> Quantum Dots.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40751687.
- Also identified by DOI 10.1021/acsnano.5c06716 and PMC identifier 12356124.
- 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 Outstanding optoelectronic properties of lead halide perovskites have been related to the formation of polarons. Nevertheless, the observation of the atomistic deformation brought about by one electron-hole pair in these materials has remained elusive. Here, we measure the transient structure of single CsPbBr<sub>3</sub> quantum dots (QDs) after resonant excitation in the single exciton limit using serial femtosecond crystallography (SFX). By reconstructing the three-dimensional (3D) differential diffraction pattern and building on density functional theory (DFT) calculations, we assign the lattice distortion after photoexcitation to the combined presence of a delocalized electron and a localized hole, forming a mixed large/small exciton-polaron. This result creates a clear picture of the polaronic deformation in CsPbBr<sub>3</sub> QDs and demonstrates the exceptional sensitivity of SFX to lattice distortions in few-nanometer crystallites. We plan to use this experimental platform for future studies of electron-lattice interactions.