Probing Femtosecond Lattice Displacement upon Photo-carrier generation in Lead Halide Perovskite
| Autor: | Batignani, Giovanni, Fumero, Giuseppe, Kandada, Ajay Ram Srimath, Cerullo, Giulio, Gandini, Marina, Ferrante, Carino, Petrozza, Annamaria, Scopigno, Tullio |
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| Rok vydání: | 2017 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1038/s41467-018-04367-6 |
| Popis: | Electronic properties and lattice vibrations are supposed to be strongly correlated in metal-halide perovskites, due to the "soft" fluctuating nature of their crystal lattice. Thus, unveiling electron-phonon coupling dynamics upon ultra-fast photoexcitation is necessary for understanding the optoelectronic behaviour of the semiconductor. Here, we use impulsive vibrational spectroscopy to reveal ground and excited state vibrational modes of methylammonium lead-bromide perovskite. We observe a coherent phonon at 106 cm-1 (13 meV), pertaining to the inorganic octahedral, which is peculiar of the electronic excited state and generated via displacive excitation mechanism. This indicates the formation of a new geometry, reached after a quarter of the phonon period T/4=80 fs, and fully equilibrated within the phonon lifetime of about 1 ps. Our observations unambiguously prove that this mode drives the crystalline distortion occurring upon carrier generation, implying the presence of polaronic effects. Comment: 8 pages, 2 figures |
| Databáze: | arXiv |
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