Direct Observation of the Exciton-Polaron in Single CsPbBr3 Quantum Dots
journal contribution
posted on 2025-09-29, 06:06 authored by Zhou Shen, Margarita Samoli, Onur Erdem, Johan Bielecki, Amit K Samanta, Juncheng E, Armando D Estillore, Chan Kim, Yoonhee Kim, Jayanath Koliyadu, Romain Letrun, Federico Locardi, Jannik Lübke, Abhishek Mall, Diogo VM Melo, Grant Mills, Safi Rafie-Zinedine, Adam Round, Tokushi Sato, Raphael de Wijn, Tamme Wollweber, Lena Worbs, Yulong Zhuang, Adrian MancusoAdrian Mancuso, Richard Bean, Henry N Chapman, Jochen Küpper, Ivan Infante, Holger Lange, Zeger Hens, Kartik AyyerThe 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 CsPbBr3quantum 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 CsPbBr3QDs 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.<p></p>
