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Communication Dans Un Congrès Année : 2023

Ultrafast exciton dynamics in colloidal 2D perovksite nanoplatelets

Elsa Cassette

Résumé

Using femtosecond transient absorption (fs-TA), we investigate the hot exciton relaxation dynamics in strongly confined lead iodide perovskite nanoplatelets (NPLs). The large quantum and dielectric confinement leads to discrete excitonic transitions and strong carrier-induced Stark features in the TA spectra. This prevents the use of conventional relaxation analysis methods [1] extracting the carrier temperature or measuring the buildup of the band- edge bleaching. Instead, we show that the TA spectral lineshape near the band-edge reflects the state of the system, which evolution in time can be used to probe the exciton cooling dynamics (Figure 1). The ultrafast hot exciton relaxation in one- to three- monolayer-thick NPLs confirms the absence of intrinsic phonon bottleneck. Indeed, the measured exciton cooling time suprisingly decreases for thinner NPLs. However, excitation fluence-dependent measurements reveal a hot phonon bottleneck effect, with a delayed relaxation when increasing the exciton density. This hot phonon bottleneck effect is found to be independent of the nature of the internal cations (organic versus inorganic), in contrast with 3D perovskites [2]. However, it is strongly affected by the ligands and/or sample surface state. Together, these results suggest a role of the surface ligands in the cooling process in these ultrathin colloidal 2D nanostructures [3]. References [1] Mingjie Li, Jianhui Fu, Qiang Xu and Tze Chien Sum, Slow Hot-Carrier Cooling in Halide Perovskites: Prospects for Hot-Carrier Solar Cells, Adv. Mater. 31, 47 (2019) [2] Thomas R. Hopper, Andrei Gorodetsky, Jarvist M. Frost, Christian Muller, Robert Lovrincic and Artem A. Bakulin, Ultrafast Intrband Spectroscopy of Hot-Carrier Cooling in Lead-Halide Perovskites, ACS Energy Lett. 3, 9 (2018) [3] Carolina Villamil Franco, Gaelle Trippée-Allard, Benoît Mahler, Christian Cornaggia, Jean-Sebastien Lauret, Thomas Gustavsson and Elsa Cassette, Exciton Cooling in 2D Perovskite Nanoplatelets: Rationalized Carrier-Induced Stark and Phonon Bottleneck Effects, J. Phys. Chem. Lett. 13, 1 (2022)
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Dates et versions

hal-04399806 , version 1 (17-01-2024)

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  • HAL Id : hal-04399806 , version 1

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Elsa Cassette. Ultrafast exciton dynamics in colloidal 2D perovksite nanoplatelets. Colloque du GDR/GDR-I HOWDI, May 2023, Porquerolles, France. ⟨hal-04399806⟩
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