Structural Evolution and Photoluminescence Quenching across the FASnI3–xBrx (x = 0–3) Perovskites - Fonctions Optiques pour les Technologies de l'informatiON - Site INSA Rennes Accéder directement au contenu
Article Dans Une Revue Journal of the American Chemical Society Année : 2024

Structural Evolution and Photoluminescence Quenching across the FASnI3–xBrx (x = 0–3) Perovskites

Adam Balvanz
Daehan Kim
Evan H. Oriel
Claudine Katan
Christos Malliakas
Richard Schaller
Lin X. Chen
Ram Seshadri
Mercouri Kanatzidis

Résumé

One of the primary methods for band gap tuning in metal halide perovskites has been halide (I/Br) mixing. Despite widespread usage of this type of chemical substitution in perovskite photovoltaics, there is still little understanding of the structural impacts of halide alloying, with the assumption being the formation of ideal solid solutions. The FASnI$_{3–x}$Br$_x$ (x = 0–3) family of compounds provides the first example where the assumption breaks down, as the composition space is broken into two unique regimes (x = 0–2.9; x = 2.9–3) based on their average structure with the former having a 3D and the latter having an extended 3D (pseudo 0D) structure. Pair distribution function (PDF) analyses further suggest a dynamic 5s2 lone pair expression resulting in increasing levels of off-centering of the central Sn as the Br concentration is increased. These antiferroelectric distortions indicate that even the x = 0–2.9 phase space behaves as a nonideal solid-solution on a more local scale. Solid-state NMR confirms the difference in local structure yielding greater insight into the chemical nature and local distributions of the FA+ cation. In contrast to the FAPbI$_3$–xBr$_x$ series, a drastic photoluminescence (PL) quenching is observed with x ≥ 1.9 compounds having no observable PL. Our detailed studies attribute this quenching to structural transitions induced by the distortions of the [SnBr$_6$] octahedra in response to stereochemically expressed lone pairs of electrons. This is confirmed through density functional theory, having a direct impact on the electronic structure.
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Dates et versions

hal-04596421 , version 1 (03-06-2024)

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Adam Balvanz, Majid Safdari, Marios Zacharias, Daehan Kim, Claire Welton, et al.. Structural Evolution and Photoluminescence Quenching across the FASnI3–xBrx (x = 0–3) Perovskites. Journal of the American Chemical Society, 2024, 146 (23), pp.16128-16147. ⟨10.1021/jacs.4c03669⟩. ⟨hal-04596421⟩
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