Electron-phonon couplings inherent in polarons drive exciton dynamics in two-dimensional metal-halide perovskites

Abstract

We report on the exciton formation and relaxation dynamics following photocarrier injection in a single-layer two-dimensional lead-iodide perovskite. We probe the time evolution of four distinct exciton resonances by means of time-resolved photoluminescence and transient absorption spectroscopies, and find that at 5\,K a subset of excitons form on a $\lesssim$ 1-ps timescale, and that these relax subsequently to lower-energy excitons on $\sim$ 5--10\,ps with a marked temperature dependence over $<$ 100\,K. We implement a mode projection analysis that determines the relative contribution of all observed phonons with frequency $\le$50\,cm${}^{-1}$ to inter-exciton nonadiabatic coupling, which in turn determines the rate of exciton relaxation. This analysis ranks the relative contribution of the phonons that participate in polaronic lattice distortions to the exciton inter-conversion dynamics and thus establishes their role in the nonadiabatic mixing of exciton states, and this in the exciton relaxation rate.

arXiv commentThis is a manuscript submitted to the Jean-Luc Brédas Festschrift in Chemistry of Materials

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Cited by in corpus (7)

• Perspective: Exciton polarons in two-dimensional hybrid metal-halide perovskites
• Photophysics of Two-Dimensional Semiconducting Organic-Inorganic Metal-Halide Perovskites
• Stochastic scattering theory for excitation induced dephasing: Time-dependent nonlinear coherent exciton lineshapes
• Homogeneous optical linewidths in hybrid Ruddlesden-Popper metal halides can only be measured using nonlinear spectroscopy
• The Optical Signatures of Stochastic Processes in Many-Body Exciton Scattering
• Stochastic scattering theory for excitation induced dephasing: Comparison to the Anderson-Kubo lineshape
• Renormalization of excitonic properties by polar phonons