The substitution of lead(II) with copper(I) and antimony(III) yields the double perovskite (a layered derivative of the ?Cs2CuSbCl6 perovskite), which exhibits an optimal bandgap energy (Eg ? 1.0 eV), making it a promising candidate for photovoltaic applications [1,2]. The deposition of this material onto substrates is strongly influenced by the choice of solvents. In this context, organic ligands such as dimethyl sulfoxide (DMSO) have emerged as effective structure-directing agents [3]. However, DMSO also exhibits additional properties, acting, for example, as an oxidizing agent, which can significantly alter the oxidation states of the precursors during perovskite nucleation and growth. Herein, the synthesis of ?Cs4CuSb2Cl12 was investigated via a solution-based chemical route, and the role of DMSO in directing the crystallization pathway was evaluated. The perovskite powder was synthesized from a stoichiometric acidic solution of CsCl, CuCl, and SbCl3. In an alternative route, CuCl2 and SbCl3 were initially dissolved in DMSO prior to mixing. In both approaches, the powders were precipitated by the dropwise addition of the precursor solution into isopropanol, resulting in the immediate formation of a dark-colored solid. Diffuse reflectance spectroscopy revealed broad absorption across the visible range, with an estimated bandgap of ~1.2 eV. X-ray diffraction confirmed the formation of a highly crystalline Cs4CuSb2Cl12? phase (monoclinic, C2/m); however, minor peaks corresponding to Cs3Sb2Cl9 were detected in samples prepared without DMSO. Notably, DMSO affects the local structure by reducing the average Cu–Cl bond length from 2.4737 Å to 2.4231 Å and the Sb–Cl bond length from 2.6812 Å to 2.6760 Å. This contraction leads to increased bond valences, from 1.29 to 1.37 v.u. for the ?CuCl6 octahedra and from 2.88 to 3.06 v.u. for the SbCl6 octahedra. These findings support the hypothesis that DMSO coordinates with Cu+ and Sb3+ ions, promoting the selective formation of the layered Cs4CuSb2Cl12 phase while suppressing competing pathways. The reaction mechanism and structural implications of DMSO coordination will be discussed further.???
Acknowledgements: Fapesp (processes 2024/18568-8, 2024/18833-3, and 2023/09820-2).
Comissão Organizadora
Pedro Alves da Silva Autreto
Comissão Científica
Ferramenta completa de submissão, avaliação e publicação de anais para eventos científicos.
