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arXiv · 2309.04338

Exciton-carrier coupling in a metal halide perovskite nanocrystal assembly probed by two-dimensional coherent spectroscopy

Esteban Rojas-Gatjens·David Otto Tiede·Katherine A. Koch·Carlos Romero-Perez·Juan F. Galisteo-Lopez·Mauricio E. Calvo·Hernan Miguez·Ajay Ram Srimath Kandada
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Abstract

The surface chemistry and inter-connectivity within perovskite nanocrystals play a critical role in determining the electronic interactions. They manifest in the Coulomb screening of electron-hole correlations and the carrier relaxation dynamics, among other many-body processes. Here, we characterize the coupling between the exciton and free carrier states close to the band-edge in a ligand-free formamidinium lead bromide nanocrystal assembly via two-dimensional coherent spectroscopy. The optical signatures observed in this work show: (i) a nonlinear spectral lineshape reminiscent of Fano-like interference that evidences the coupling between discrete electronic states and a continuum, (ii) symmetric excited state absorption cross-peaks that suggest the existence of a coupled exciton-carrier excited state, and (iii) ultrafast carrier thermalization and exciton formation. Our results highlight the presence of coherent coupling between exciton and free carriers, particularly in the sub-100 femtosecond timescales.

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Esteban Rojas-Gatjens, David Otto Tiede, Katherine A. Koch, Carlos Romero-Perez, Juan F. Galisteo-Lopez, Mauricio E. Calvo, Hernan Miguez, Ajay Ram Srimath Kandada. 2023-09-08. Exciton-carrier coupling in a metal halide perovskite nanocrystal assembly probed by two-dimensional coherent spectroscopy. https://arxiv.org/abs/2309.04338

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