# Simultaneous Existence of Confined and Delocalized Vibrational Modes in Colloidal Quantum Dots

## TL;DR

This study reveals the coexistence of confined and delocalized vibrational modes in colloidal quantum dots, which strongly couple to excitons, using advanced spectroscopy and simulation to clarify phonon-exciton interactions.

## Contribution

It demonstrates the simultaneous presence of confined and delocalized vibrational modes in colloidal quantum dots and their strong coupling to excitons, advancing understanding of phonon interactions.

## Key findings

- Evidence of coexisting vibrational modes from lineshape analysis
- Strong exciton-phonon coupling observed in experiments
- Simulation supports the experimental interpretation

## Abstract

Coupling to phonon modes is a primary mechanism of excitonic dephasing and energy loss in semiconductors. However, low-energy phonons in colloidal quantum dots and their coupling to excitons are poorly understood, since their experimental signatures are weak and usually obscured by unavoidable inhomogeneous broadening of colloidal dot ensembles. We use multi-dimensional coherent spectroscopy at cryogenic temperatures to extract the homogeneous nonlinear optical response of excitons in a CdSe/CdZnS core/shell colloidal quantum dot ensemble. Comparison to simulation provides evidence that the observed lineshapes arise from the co-existence of confined and delocalized vibrational modes, both of which couple strongly to excitons in CdSe/CdZnS colloidal quantum dots.