Over the past few years, lead halide perovskites have emerged as a class of dominant semiconductor materials in the photovoltaic (PV) field with an unprecedented sharp enhancement of power conversion efficiencies (PCEs) up to 22.1%, as well as in other promising optoelectronic applications due to their extraordinary and unique properties. However, the lead toxicity and long-term stability of these lead-based perovskites have raised considerable concerns for their real applications. Exploration of potentially low-toxic metal halide perovskite materials becomes one of the significant pivotal challenges in this century for PV, optoelectronic, and other unexplored applications. In this review, we summarize the recent progress on the development of low-toxic metal halide perovskites with a particular focus on their structures and properties, and discuss their potential applications in PV and optoelectronic devices. Moreover, we suggest current challenges and future research directions with the goal of stimulating further research interest and potential applications

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The perovskite layer is a crucial component influencing high-performance perovskite solar cells (PSCs). In the one-step solution method, anti-solvents are important for obtaining smooth and uniform perovskite active layers. This work explored the effect of various anti-solvents on the preparation of triple cation perovskite active layers. In general, anti-solvents with low dielectric constants, low polarity, and low boiling point are suitable for the preparation of perovskite films. Microstructural and elemental analyses of the perovskite films were systematically conducted by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The photoelectric properties, carrier transfer, and recombination process in the PSCs were investigated using photocurrent-voltage characteristic curves and electrochemical impedance spectroscopy. Optimum performance was obtained when the anti-solvent was diethyl ether (DEE) and the ratio of the optimum amount of DEE to the volume of the precursor was 1 : 10. Meanwhile, we found that the partial replacement of formamidinium/methylammonium by cesium could increase the stability of the PSCs and enhance the power conversion efficiency from 15.49% to over 17.38%.

Carbon fiber is a good candidate in various applications, including in the military, structural, sports equipment, energy storage, and infrastructure. Coloring of carbon fiber has been a big challenge for decades due to their high degrees of crystallization and insufficient chemical affinity to dyes. Here, multicolored carbon fiber fabrics are fabricated using a feasible and effective atomic layer deposition (ALD) technique. The vibrant and uniform structural colors originating from thin-film interference is simply regulated by controlling the thickness of conformal TiO coatings on the surface of black carbon fibers. Impressively, the colorful coatings show excellent laundering durability, which can endure 50 cycles of domestic launderings. Moreover, the mechanical properties only drop off slightly after coloring. Overall, these results open an alternative avenue for development of TiO nanostructured films with multifunctional features grown using ALD technologies. This technology is speculated to have potential applications in various fields such as color engineering and radiation-proof fabrics and will further guide material design for future innovations in functional optical and color-display devices. More importantly, this research demonstrates a route for the coloring of black carbon fiber-based materials with vibrant colors.

Solid oxide fuel cells (SOFC) are highly efficient energy conversion device, but its high operating temperature (800∼1000 °C) restricts industrial commercialization. Reducing the operating temperature to <800 °C could broaden the selection of materials, improve the reliability of the system, and lower the operating cost. However, traditional perovskite cathode could not both attain the high catalytic activity towards the oxygen reduction reaction and good durability at medium and low temperature range. In contrast to the conventional perovskites, Ruddlesden–Popper perovskites exhibit fast oxygen surface exchange kinetic and excellent stability at medium and low temperatures, and excel both in oxide-conducting fuel cells (O-SOFC) and proton-conducting fuel cells (H-SOFC). In this paper, we try to relate its prominent performance with the crystal structure, main physical properties, and transport mechanism of oxygen ions and protons. We also summarize the current strategy in improving its application in O-SOFC and H-SOFC. Finally, we discuss the challenges and outlook for the future development of RP perovskites in SOFC.

We consider the weakly nonlinear three‐wave interactions in an isothermal atmosphere. The mutual interactions among the three linear branches of dynamical‐thermodynamical atmospheric motions (gravity waves, acoustic waves, and vortical motions) are investigated. In addition to the resonant case, nonresonant interactions are also considered. On the basis of the analytical solution of the linearized wave‐amplitude equation with possible existence of a frequency mismatch, the resonance surface, the interaction domain, and growth time in three‐dimensional geometry in k‐space in various cases have been calculated and some numerical results are given. It is found that the nonresonant interaction can be very important, especially when a gravity wave and two vortical modes of motions interact as a nonresonant trio. The energy transfer from the gravity wave to vortical motions might limit the growth of the gravity wave amplitude and hence might provide a reasonable mechanism for gravity waves to saturate in the middle atmosphere.

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