We dive deeper into the rich many-body physics at the heart of excitons, primary photoexcitations, in two-dimensional lead-halide perovskites. Their polaronic nature, already a product of exciton-phonon interactions, is revealed to also impact their mutual interactions. Using non-linear coherent spectroscopy, we reveal that the polaronic cloud surrounding excitons shield them from inelastic scattering, making this interaction a thousand times weaker than other non-polaronic two-dimensionnal semiconductors. This observation is a new important insight into polaron many-body physics where insights from simulations remain scarce.
