Regensburg 2025 – scientific programme
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O: Fachverband Oberflächenphysik
O 74: Poster Metal and Semiconductor Substrates: Structure, Epitaxy and Growth
O 74.3: Poster
Wednesday, March 19, 2025, 18:00–20:00, P2
On-surface fabrication of cesium tin halide nanostructures deviating from the perovskite ABX3 structure — Madad Abbasli, Dina Wilks, Carsten Busse, and •Robin Ohmann — University of Siegen, Siegen, Germany
We demonstrate that evaporation of the precursor molecules CsBr and SnBr2 onto an atomically clean gold surface not only leads to the expected stoichiometric CsSnBr3 structure, but also yields a range of other distinct structures. The experiments were conducted in ultra-high vacuum and investigated by scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). When deposited on Au(111), we observe a flower structure with hexagonal symmetry tentatively assigned to Cs2SnBr6, a ladder structure, a stripe pattern, a honeycomb structure, and a large square structure. The emergence of these structures depends on surface coverage - either submonolayer or multiple monolayers - and on the relative proportions of the two precursor molecules. In contrast, on Au(100) these structures are not observed, suggesting that the interface is playing a crucial role. The structures are compared with those formed by depositing either CsBr or SnBr2 on Au(111). While a honeycomb structure can also be formed with SnBr2 alone, the other structures bear no resemblence to either pure component. Thus, they are assigned to structures involving specific ratios of Cs, Sn and Br deviating from the standard ABX3 structure. The structural variability underscores the importance of precise deposition conditions and interface selection in the fabrication of perovskite materials.
Keywords: Perovskite; Epitaxial growth; Surface; Scanning tunneling microscopy; Low-energy electron diffraction