Despite the rapid development and enormous success of organic–inorganic hybrid halide perovskites (AB′X 3), such as CH3NH3PbI3 as absorbers for perovskite-based solar cells (PSCs), the commercial applications of photovoltaic techniques still face several challenges, such as decomposition when exposed to light and moisture, and lead toxicity. On the other hand, the double perovskites (A 2 B′B″X 6) are derived from the AB′X 3 when half of the octahedrally coordinated B′-cations are partially replaced by the suitable B″-cations. They are attracting attention due to a new design strategy to replace Pb2+ ions with the couple of a monovalent M + ion and a trivalent M 3+ ion, leading to a new family of quaternary double perovskites. In this way, we aim to synthesize and characterize Cs2AgSbCl6 powdered samples, designed for solar cell applications. The crystalline phase and morphological features are investigated by X-ray powder diffraction (XRPD), neutron powder diffraction (NPD), scanning electron microscopy (SEM) in complement with UV–vis spectroscopy, showing a suitable band gap of 2.7 eV. The solution synthesis method proved to be efficient in obtaining polycrystalline-Cs2AgSbCl6 samples in a cubic ordered phase. DFT calculations also provided insights on the vibrational properties of Cs2AgSbCl6, corroborating the experimental data and elucidating the optical activity of Raman and infrared modes.

Two-dimensional (2D) layered metal halide perovskites have recently received a lot of attention due to their possible applications as photovoltaic and optoelectronic materials. Rubidium di-tin pentabromide, RbSn2Br5, is a promising...

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Among chalcogenide thermoelectric materials, SnTe is an excellent candidate for intermediate temperature applications, in replacement of toxic PbTe. We have prepared pure polycrystalline SnTe by arc melting, and investigated the structural evolution by temperature-dependent neutron powder diffraction (NPD) from room temperature up to 973 K. In this temperature range, the sample is cubic (space group Fm-3m) and shows considerably larger displacement parameters for Te than for Sn. The structural analysis allowed the determination of the Debye model parameters and provided information on the Sn–Te chemical bonds. SEM images show a conspicuous nanostructuration in layers below 30 nm thick, which contributes to the reduction of the thermal conductivity down to 2.5 W/m·K at 800 K. The SPS treatment seems to reduce the number of Sn vacancies, thus diminishing the carrier density and increasing the Seebeck coefficient, which reaches 60 μV K−1 at 700 K, as well as the weighted mobility, almost doubled compared with that of the as-grown sample.