Article Dans Une Revue Chemistry of Materials Année : 2024

Low-Temperature Persistent Disorder and Lattice Dynamics in a Luminescent 1D Hybrid Lead Halide: Implications and Insights

Résumé

Hybrid organic–inorganic halides have traditionally been viewed as materials that adopt well-ordered structural phases at low temperatures. In this article, we report a one-dimensional perovskitoid aminoguanidinium lead iodide (AGAPbI3) with a first-order phase transition at 400/369 K (during heating/cooling) that breaks away from this rule. Specifically, we demonstrate that the structural transformation to the low-temperature monoclinic C2/c phase does not entirely suppress the motions associated with the organic AGA+ cation, leading to a phenomenon which we call now a persistent disorder. Indeed, it is still possible to observe pronounced dynamics of its terminal NH2 group at least, which gradually slows down upon cooling and impacts the PbI64– octahedra. As a result, we observe an unusually high activation energy of 0.6 eV related to the low-temperature relaxation dynamics, which is approximately 1 order of magnitude higher than those observed in conventional hybrid halides. We illustrate that the ongoing dynamic processes profoundly influence the temperature-dependent third-harmonic generation response and photoluminescence, the latter of which is characterized by two broad emission peaks with large Stokes shifts. Lastly, we emphasize that AGA+ cations can adopt two symmetry-equivalent positions within the low-temperature phase of AGAPbI3, revealing the ongoing transition between the low-temperature static and high-temperature dynamic disorder types in this hybrid compound.

Dates et versions

hal-04994126 , version 1 (17-03-2025)

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Andrzej Nowok, Mirosław Mączka, Anna Gągor, Maciej Ptak, Jan Zaręba, et al.. Low-Temperature Persistent Disorder and Lattice Dynamics in a Luminescent 1D Hybrid Lead Halide: Implications and Insights. Chemistry of Materials, 2024, 36 (13), pp.6588-6597. ⟨10.1021/acs.chemmater.4c00942⟩. ⟨hal-04994126⟩
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