A clustering technique is applied using dynamic‐time‐wrapping (DTW) analysis to X‐ray diffraction (XRD) spectrum patterns in order to identify the microscopic structures of substituents introduced into the main phase of magnetic alloys. The clustering technique is found to perform well, identifying the concentrations of the substituents with success rates of ≈90%. This level of performance is attributed to the capability of DTW processing to filter out irrelevant information such as the peak intensities (due to the uncontrollability of diffraction conditions in polycrystalline samples) and the uniform shift of peak positions (due to the thermal expansion of lattices). The established framework is not limited to the system treated in this work, but is widely applicable to systems the properties of which are to be tuned by atomic substitutions within a phase. The framework has a broader potential to predict properties such as magnetic moments, optical spectra etc.) from observed XRD patterns, by predicting such properties evaluated from predicted microscopic local structure.

Perovskite materials show excellent photovoltaic performance along with simple processing and low‐energy requirements. Despite their high power conversion efficiency (PCE), instability in the presence of moisture is still a major challenge. An effective method to enhance perovskite stability is by reducing dimensionality through incorporation of long organic cations into the perovskite crystal, which improves charge‐carrier extraction efficiency of the perovskites compared to conventional 3D perovskites. Quasi‐2D perovskites or 2D/3D perovskites strike a good balance between PCE and stability, having much improved stability compared to 3D structures while retaining excellent optoelectronic properties. Yielding better thermal stability and broader absorption into the near‐infrared, formamidinium iodide (FAI) doping has positive influences yet tends to cause poor surface morphology. Here, we introduce highly stable MA/FA‐based quasi‐2D perovskite fabricated by mixed cation doping (MCD), which is repeated deposition of MA and FA cations onto a quasi‐2D perovskite layer. MCD enables better morphology and surface passivation, leading to fewer defects. MA/FA‐based quasi‐2D perovskite with quasi‐cubic structure has high humidity resistivity, remaining intact after 90 days under 60% relative humidity without encapsulation. The underlying mechanism is further explained by binding and formation energies of cation mixture in solution and perovskite structure through computational analysis.

Two interacting double quantum dots (DQDs) can be suitable candidates for operation in the applications of quantum information processing and computation. In this work, DQDs are modeled by the heterostructure of two-dimensional (2D) MoS2 having 1T-phase embedded in 2H-phase with the aim to investigate the feasibility of controlled-NOT (CNOT) gate operation with the Coulomb interaction. The Hamiltonian of the system is constructed by two models, namely the 2D electronic potential model and the 4×4 matrix model whose matrix elements are computed from the approximated two-level systems interaction. The dynamics of states are carried out by the Crank–Nicolson method in the potential model and by the fourth order Runge–Kutta method in the matrix model. Model parameters are analyzed to optimize the CNOT operation feasibility and fidelity, and investigate the behaviors of DQDs in different regimes. Results from both models are in excellent agreement, indicating that the constructed matrix model can be used to simulate dynamical behaviors of two interacting DQDs with lower computational resources. For CNOT operation, the two DQD systems with the Coulomb interaction are feasible, though optimization of engineering parameters is needed to achieve optimal fidelity.

Quasi‐2D perovskites strike a good balance between high performance and stability for solar cell applications. Formamidinium iodide doping could improve thermal stability and broaden optical absorption, yet tends to cause poor morphology. The work featured on this cover presents a new strategy to optimize the morphology, electronic properties, and humidity resistivity through mixed cation doping (MCD) and gradual deposition of methylammonium and formamidinium cations onto the perovskite layer. The underlying mechanism is revealed by interaction energies of cation mixtures in solution and computational analysis of perovskite structures. More information can be found in the Full Paper by Pongsakorn Kanjanaboos et al. on page 1280 in Issue 10, 2019 (DOI: 10.1002/cnma.201900189).