Quantifying Photoinduced Polaronic Distortions in Inorganic Lead Halide Perovskites Nanocrystals
| Autor: | Cannelli, Oliviero, Colonna, Nicola, Puppin, Michele, Rossi, Thomas, Kinschel, Dominik, Leroy, Ludmila, Loeffler, Janina, March, Anne Marie, Doumy, Gilles, Haddad, Andre Al, Tu, Ming-Feng, Kumagai, Yoshiaki, Walko, Donald, Smolentsev, Grigory, Krieg, Franziska, Boehme, Simon C., Kovalenko, Maksym V., Chergui, Majed, Mancini, Giulia F. |
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| Rok vydání: | 2021 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | The development of next generation perovskite-based optoelectronic devices relies critically on the understanding of the interaction between charge carriers and the polar lattice in out-of-equilibrium conditions. While it has become increasingly evident for CsPbBr3 perovskites that the Pb-Br framework flexibility plays a key role in their light-activated functionality, the corresponding local structural rearrangement has not yet been unambiguously identified. In this work, we demonstrate that the photoinduced lattice changes in the system are due to a specific polaronic distortion, associated with the activation of a longitudinal optical phonon mode at 18 meV by electron-phonon coupling, and we quantify the associated structural changes with atomic-level precision. Key to this achievement is the combination of time-resolved and temperature-dependent studies at Br K-edge and Pb L3-edge X-ray absorption with refined ab-initio simulations, which fully account for the screened core-hole final state effects on the X-ray absorption spectra. From the temporal kinetics, we show that carrier recombination reversibly unlocks the structural deformation at both Br and Pb sites. The comparison with the temperature-dependent XAS results rules out thermal effects as the primary source of distortion of the Pb-Br bonding motif during photoexcitation. Our work provides a comprehensive description of the CsPbBr3 perovskites photophysics, offering novel insights on the light-induced response of the system and its exceptional optoelectronic properties. Comment: Main: 27 pages, 4 figures SI: 16 pages, 8 figures |
| Databáze: | arXiv |
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