Chloride-Promoted Formation of a Bimetallic Nanocluster Au₈₀Ag₃₀ and the Total Structure Determination

We report the total structure determination of a large bimetallic nanocluster with an overall composition of [Au₈₀Ag₃₀(CCPh)₄₂Cl₉]­Cl. It is the largest structurally characterized bimetallic coinage nanocluster so far. The 110 metal atoms are distributed in a concentric four-shell Russian doll arrangement, Au₆@Au₃₅@Ag₃₀Au₁₈@Au₂₁. There are 42 PhCC ligands and 9 μ₂-chloride ligands clamping on the cluster surface. The chloride is proven to be critical for the formation of this giant cluster, as the control experiment in the absence of halide gives only smaller species. This work demonstrates that the halide can play a key role in the formation of a large metal nanocluster, and the halide effect should be considered in the design and synthesis of metal nanoclusters

[Mn^IIIMn^IV₂Mo₁₄O₅₆]^17–: A Mixed-Valence Meso-Polyoxometalate Anion Encapsulated by a 64-Nuclearity Silver Cluster

A 64-nuclearity silver cluster encapsulating a unique POM anion [Mn^IIIMn^IV₂Mo₁₄O₅₆]^17– has been synthesized. The formation of the templating core performs a reassembly process for increasing nuclearities from {MnMo₉} to {Mn₃Mo₁₄}. It represents a rare inorganic meso anion containing mixed-valent Mn that is built up by d-{Mn^IVMo₇} and l-{Mn^IVMo₇} units connecting together through a {Mn^III} fragment

Understanding the Cubic Phase Stabilization and Crystallization Kinetics in Mixed Cations and Halides Perovskite Single Crystals

The spontaneous α-to-δ phase transition of the formamidinium-based (FA) lead halide perovskite hinders its large scale application in solar cells. Though this phase transition can be inhibited by alloying with methylammonium-based (MA) perovskite, the underlying mechanism is largely unexplored. In this Communication, we grow high-quality mixed cations and halides perovskite single crystals (FAPbI₃)_1–<i>x</i>(MAPbBr₃)_<i>x</i> to understand the principles for maintaining pure perovskite phase, which is essential to device optimization. We demonstrate that the best composition for a perfect α-phase perovskite without segregation is <i>x</i> = 0.1–0.15, and such a mixed perovskite exhibits carrier lifetime as long as 11.0 μs, which is over 20 times of that of FAPbI₃ single crystal. Powder XRD, single crystal XRD and FT-IR results reveal that the incorporation of MA⁺ is critical for tuning the effective Goldschmidt tolerance factor toward the ideal value of 1 and lowering the Gibbs free energy via unit cell contraction and cation disorder. Moreover, we find that Br incorporation can effectively control the perovskite crystallization kinetics and reduce defect density to acquire high-quality single crystals with significant inhibition of δ-phase. These findings benefit the understanding of α-phase stabilization behavior, and have led to fabrication of perovskite solar cells with highest efficiency of 19.9% via solvent management

Understanding the Cubic Phase Stabilization and Crystallization Kinetics in Mixed Cations and Halides Perovskite Single Crystals

The spontaneous α-to-δ phase transition of the formamidinium-based (FA) lead halide perovskite hinders its large scale application in solar cells. Though this phase transition can be inhibited by alloying with methylammonium-based (MA) perovskite, the underlying mechanism is largely unexplored. In this Communication, we grow high-quality mixed cations and halides perovskite single crystals (FAPbI₃)_1–<i>x</i>(MAPbBr₃)_<i>x</i> to understand the principles for maintaining pure perovskite phase, which is essential to device optimization. We demonstrate that the best composition for a perfect α-phase perovskite without segregation is <i>x</i> = 0.1–0.15, and such a mixed perovskite exhibits carrier lifetime as long as 11.0 μs, which is over 20 times of that of FAPbI₃ single crystal. Powder XRD, single crystal XRD and FT-IR results reveal that the incorporation of MA⁺ is critical for tuning the effective Goldschmidt tolerance factor toward the ideal value of 1 and lowering the Gibbs free energy via unit cell contraction and cation disorder. Moreover, we find that Br incorporation can effectively control the perovskite crystallization kinetics and reduce defect density to acquire high-quality single crystals with significant inhibition of δ-phase. These findings benefit the understanding of α-phase stabilization behavior, and have led to fabrication of perovskite solar cells with highest efficiency of 19.9% via solvent management