Manipulating polaron dynamics for effective exciton transfer in isomeric lead halide perovskites

The study of exciton transfer in two-dimensional (2D) hybrid lead halide perovskites (LHPs) is crucial for understanding the dynamic processes of exciton states and optimizing their optoelectronic properties. However, the underlying mechanisms governing the transfer between different excitonic states remain elusive. In this work, through structural analysis, high-pressure spectroscopic experiments, and theoretical calculations, we demonstrate that the transfer between free excitons (FEs) and self-trapped excitons (STEs) in 2D LHPs is closely linked to the stability of exciton polarons. Through rational design of organic cation spatial configurations and modulation of intermolecular van der Waals interactions, the lattice dynamics in LHPs can be deterministically tailored, thereby controlling both the formation of exciton polarons and the highly efficient transfer between FEs and STEs. This study provides fundamental understanding of the exciton transfer mechanisms in 2D LHPs, which could be applied to optimize their optoelectronic properties.