arXiv subjects

Pascal Rusch

Publications and source records attributed to Pascal Rusch.

4 recordsLinked to original sources

arXiv2026

A Nanocrystal Synthesis Derived Approach to Silver Bismuth Iodide Layered Double Perovskites with Aliphatic Amines: (CnH(2n+1)NH3)4AgBiI8

Lead-free iodide double perovskites are an interesting class of materials since they combine a relatively low toxicity (compared to the lead counterpart) with the small bandgap typical of iodide-based perovskite structures. Their reported number is small due to their lower structural stability compared to the chloride and bromide analogues, hence their difficult synthesis. The structural constraints that limit stability, on the other hand, can be much relieved in layered, organic-inorganic perovskites. Following this line of thought, we report here a successful fast precipitation route to iodide layered (CnH(2n+1)NH3)4AgBiI8 (n = 10, 12, and 14) double perovskites that borrow concepts from the synthesis of colloidal nanocrystals. X-ray diffraction studies revealed for these compounds a monoclinic crystal structure containing edge-sharing alternated [AgI6] and [BiI6] octahedra. These materials have experimental band gaps of 2.1 eV, as also corroborated by theoretical calculations. We have also investigated their phase transitions by thermal analysis and temperature-dependent diffraction and found them to be similar to their lead-based layered perovskite counterparts.

cond-mat.mtrl-sci↗

arXiv2026

Synthesis and Structural Analysis of an Emissive Colloidal Argyrodite Nanocrystal: Canfieldite Ag8SnS6

We resolve a phase identification controversy in the Ag-Sn-S material system by unraveling the polymorphic structure of nanocrystals within the argyrodite material family. Argyrodites are a class of superionic materials used in their bulk form for applications in solid-state batteries and thermoelectrics, where their advantageous properties relate to their polymorphism. However, despite their well-studied bulk applications, the limited exploration at the nanoscale has left considerable potential for the discovery of emerging properties due to size effects. Further, phase identification presents a prominent challenge to the study of polymorphs in superionic conductors and related mate-rials. In this work, we synthesize canfieldite-like (Ag8SnS6) nanocrystals to understand their formation and structural behavior at the nanoscale. We observe the emergence of emissive, meta-stable, cluster-like species. Then, high-resolution transmission electron microscopy reveals indistinguishable polymorphs of canfieldite due to identical heavy-atom frameworks. However, using synchrotron X-ray total scattering for pair distribution function analysis, we uncover structural distortions, showing a pseudo-orthorhombic configuration that likely gives rise to the red emission. Further, we investigate the optical properties and structure of Ag8SnS6 nanocrystals upon the addition of Zn2+, the cation of interest in the canfieldite vs. pirquitasite (Ag2ZnSnS4) phase identification controversy. We show that Zn2+ is incorporated in the canfieldite-like structure through the replacement of Ag+, boosting the emission. Our results solve a standing phase identification challenge and uncover fundamental insights for the synthesis and structure of canfieldite nanocrystals, laying the ground for the exploration of other argyrodite materials with emerging properties at the nanoscale.

cond-mat.mtrl-sci↗

arXiv2025

Synthesis, Growth Mechanism, and Photocatalytic Properties of Metallic-Bi/Bi13S18Br2 Nano-Bell Heterostructures

We report the synthesis of bell-shaped Bi/Bi13S18Br2 metal/semiconductor heterostructures as a photocatalyst based on non-toxic and Earth-abundant elements. Their unique morphology arises from a multi-step growth process, involving 1) the nucleation of Bi13S18Br2 nanorods, 2) the reduction of a metallic-Bi domain on their surface induced by N,N-didodecylmethylamine, and 3) the heterostructure accretion by a localized reaction at the Bi/Bi13S18Br2 interface promoted by Ostwald ripening. These heterostructures display remarkable stability in polar solvents, remaining almost unaffected by prolonged exposure to isopropanol and water, and exhibit high photocatalytic efficiency for the degradation of organic dyes (i.e., Rhodamine-B and Methylene Blue) under visible-light irradiation, with good recyclability. Additionally, preliminary tests demonstrate CO2 reduction capabilities, which make them promising for both the photocatalytic degradation of pollutants and photo-electro CO2 conversion. The straightforward synthesis process and the use of non-toxic and earth-abundant elements offers significant potential for sustainable energy conversion technologies.

cond-mat.mtrl-sci↗

arXiv2025

Improving the Stability of Colloidal CsPbBr3 Nanocrystals with an Alkylphosphonium Bromide as Surface Ligand Pair

In this study, we synthesised a phosphonium-based ligand, trimethyl(tetradecyl)phosphonium bromide (TTP-Br), and employed it in the post-synthesis surface treatment of Cs-oleate-capped CsPbBr3 NCs. The photoluminescence quantum yield (PLQY) of the NCs increased from 60% to more than 90%, as a consequence of replacing Cs-oleate with TTP-Br ligand pairs. Density functional theory calculations revealed that TTP+ ions bind to the NC surface by occupying Cs+ surface sites and orienting one of their P-CH3 bonds perpendicular to the surface, akin to quaternary ammonium passivation. Importantly, TTP-Br-capped NCs exhibited higher stability in air compared to didodecyldimethylammonium bromide-capped CsPbBr3 NCs (which is considered a benchmark system), retaining 90% of their PLQY after six weeks of air exposure. Light-emitting diodes fabricated with TTP-Br-capped NCs achieved a maximum external quantum efficiency of 17.2 %, demonstrating the potential of phosphonium-based molecules as surface ligands for CsPbBr3 NCs in optoelectronic applications.

cond-mat.mtrl-sci↗