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Anode‐free potassium (K) metal batteries are promising candidates in high‐energy‐density batteries. Nevertheless, the notorious potassium dendrite growth and poor K plating/stripping efficiency originating from the potassiophobicity of conventional Cu current collectors impede their practical applications. Herein, by means of systematically multi‐scale theoretical simulations, the correlations among K deposition morphology, nucleation sites, and potassiophilicity of mediation layers are well illuminated from thermodynamics and dynamics perspectives. As a proof of concept, a potassiophilic alloy Cu6Sn5 layer is constructed on commercial Cu foils via a facile electroless plating approach. The designed Cu6Sn5@Cu can guide the homogeneous distribution of K+ flux and regulate the electronic field, promoting uniform K+ plating and stripping. Meanwhile, a KF‐rich solid electrolyte interphase (SEI) layer with high mechanical strength is electrochemically induced and formed, facilitating the transport of K+ through SEI and enhancing the stability of SEI. Consequently, Cu6Sn5@Cu delivers great performance with durable stability of up to 600 h (1 mA cm−2 and 1 mAh cm−2) in no‐reservoir half‐cells. Benefiting from the unique mediation layer design, a novel anode‐free K‐metal full‐cell prototype demonstrates ameliorative cyclic stability. This work advances a fundamental understanding and establishes the bridge between the potassium deposition morphology and mediation layer properties for anode‐free potassium‐metal batteries. [ABSTRACT FROM AUTHOR]

First-principles calculations have been performed to study the effect of cation replacement with methylammonium (MA+), Cs+, and Rb+ on the properties of formamidinium lead iodide (FAPbI3) perovskite. It is found that these dopants could improve the stability of the desired α phase of FAPbI3 at reduced temperature by lowering the transition temperature between the perovskite cubic α phase and nonperovskite hexagonal δ phase. Interestingly, the optical absorption properties and the effective masses of holes of FAPbI3 perovskite are only slightly affected. The nature of the improvement of the phase stability resulting from the cation replacement is revealed. However, the calculated mixing energies indicate that these multication materials still suffer long-term instability. Our results provide theoretical guidance for improving current multication engineering strategies or even developing new approaches. [ABSTRACT FROM AUTHOR]

We have synthesized silicon nanocrystalline structures from thermal annealing of thin film amorphous silicon-based multilayers. The annealing procedure that was carried out in vacuum at temperatures up to 1100°C is integrated in a X-ray diffraction (XRD) setup for real-time monitoring of the formation phases of the nanostructures. The microstructure of the crystallized films is investigated through experimental measurements combined with atomistic simulations of realistic nanocrystalline silicon (nc-Si) models. The multilayers consisting of uniformly alternating thicknesses of hydrogenated amorphous silicon and silicon oxide (Si[O.sub.2]) were deposited by plasma enhanced chemical vapor deposition on crystalline silicon and Corning glass substrates. The crystallized structure consisting of nc-Si structures embedded in an amorphous matrix were further characterized through XRD, Raman spectroscopy, and Fourier transform infrared measurements. We are able to show the different stages of nanostructure formation and how the sizes and the crystallized mass fraction can be controlled in our experimental synthesis. The crystallized silicon structures with large crystalline filling fractions exceeding 50% have been simulated with a robust classical molecular dynamics technique. The crystalline filling fractions and structural order of nc-Si obtained from this simulation are compared with our Raman and XRD measurements. PACS Nos.: 81.10Jt, 81.07.-b, 61.05.cp. Nous fabriquons des structures nanocristallines de silicium par recuit thermique de films minces multicouches de silicium amorphe. La procedure de recuit se fait dans une chambre a vide a temperature jusqu'a 1100°C, avec un appareillage in situ de diffraction X (XRD) pour surveiller en temps reel la formation des phases nanocristallines. Nous etudions la microstructure des films cristallises a l'aide de mesures experimentales et de simulations atomiques de modeles realistes de silicium nanocristallin (nc-Si). Les multicouches sont constitues de couches uniformes alternees de silicium amorphe hydrogene et d'oxyde de silicium Si[O.sub.2] et sont obtenus par depot chimique en phase vapeur avec traitement au plasma sur des substrats de silicium cristallin et de verre Corning. Les structures cristallisees sont des structures nc-Si incrustees dans une matrice amorphe et sont caracterisees par XRD, spectroscopie Raman et par mesures infra-rouge a transformee de Fourier. Nous sommes capables de montrer les differentes etapes de la formation de nanostructure et comment les grosseurs et les fractions massiques cristallisees peuvent etre controlees dans notre montage. Nous avons simule les structures cristallisees de silicium, avec des coefficients de remplissage de plus de 50%, a l'aide une solide technique de dynamique moleculaire classique. Nous comparons les fractions de remplissage et l'ordre structural de nc-Si obtenus dans cette simulation avec nos mesures Raman et XRD. [Traduit par la Redaction], 1. Introduction Silicon quantum dots (QDs) have great potential to be an absorber in solar cells, where the band gap can be tuned by the QD size. QDs have been [...]

It has been possible to calculate geometries for medium-sized silicon clusters using an unbiased global search with a genetic algorithm. Ion mobilities determined for these geometries by trajectory calculations are strongly aligned with the values measured experimentally. This research involved undertaking an unbiased global search for the ground state structures of silicon clusters with between 11 and 20 atoms. The researchers operated with a population of 16 clusters with four 'parents.'