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Abstract Preparing organometal halide perovskite array thin films from solution is a big challenge due to its soluble nature. In this work, we provide a fast chemical vapor-solid reaction (FCVR) for fabricating perovskite array thin films. An elemental Pb array thin film was firstly prepared by magnetron sputtering using a shadow mask, which then converted to CH 3 NH 3 PbI 3 arrays by reacting with CH 3 NH 3 I. The related photoelectric characteristics were investigated by Uv–Vis spectroscopy, photoluminescence spectroscopy, and transient photovoltage analysis. The photodetector devices were assembled using these resultant perovskite thin films, which showed a fast response with 3 ms rise time and 3 ms decay time both under 405 nm and 660 nm light illumination. The response was faster than the commercial photodetector. This FCVR method not only provides a high quality perovskite array thin film, but also a novel synthesis strategy for new organic-inorganic hybrid perovskite photoelectric materials. Graphical abstract Image 1 Highlights • Fast chemical vapor-solid reaction (FCVR) was used for perovskite fabrication. • Perovskite array thin films can be easily fabricated by FCVR method. • Fast time response photodetectors were assembled. [ABSTRACT FROM AUTHOR]

• CdS under-layer reduces the recombination at Ag 2 S/FTO interface. • Photoinduced charge carrier dynamics of FTO/CdS/Ag 2 S has been studied. • CdS under-layer raise 52% PCE of Ag 2 S solar cell. [Display omitted] The recombination of photoinduced charge carriers is detrimental to the photovoltaic performance of solar cells. In this work, we used CdS as an under-layer to reduce the recombination of photoinduced charge carriers at the Ag 2 S/FTO (F-doped SnO 2) interface. The CdS under-layer was deposited onto an FTO substrate using a facile chemical bath deposition (CBD) method. By controlling the thickness of the CdS film between Ag 2 S and FTO, the recombination of photoinduced charge carriers was successfully suppressed. The effect of the CdS under-layer on the charge carrier recombination was carefully evaluated by transient surface photovoltage (TSPV) measurements, electrochemical impedance spectroscopy (EIS) and a photoelectrochemical method. The power conversion efficiency (PCE) of solar cell devices with a 40 nm CdS under-layer is 1.16%, which is ~52% enhancement compared to those of FTO/Ag 2 S-based solar cell devices. Our work may provide a useful strategy to suppress photoinduced charge carrier recombination at the electrode and absorber semiconductor interface. [ABSTRACT FROM AUTHOR]

• Nanosheets CuO and nanorods ZnO construct heterojunction material. • CuO / ZnO shows wavelength dependent charge carrier dynamics. • Photogenerated holes in CuO / ZnO may determine catalytic performance. Heterojunction materials composed of narrow and wide band-gap semiconductors possess different photoelectric responses under different wavelength incident light, and show distinct photogenerated charge carrier dynamics. In this work, taking the hydrothermal method fabricated CuO nanosheets / ZnO nanorods heterojunction materials as example, the wavelength dependent photoinduced charge carrier dynamics in this heterojunction material have been carefully studied. Transient surface photovoltage (TSPV) measurements reveal that the photogenerated holes gather at the surface of the fabricated CuO / ZnO with 355 nm light illumination, but photogenerated electrons gather at the surface under 532 nm light. Photocatalytic degradation experiments suggest that CuO / ZnO heterojunction material has better performance under ultraviolet light than that under visible light. [ABSTRACT FROM AUTHOR]

Novel high-entropy alloys (HEAs) coatings deposited using physical vapour deposition technique are potential candidates of protective coatings due to their excellent performance. However, the correlation between properties and microstructure of HEAs coatings has not been completely established and the hardening mechanism remains unclear. In this paper, the AlCrNbSiTi HEA coatings were deposited under different bias voltages by radio-frequency magnetron sputtering. The morphology, chemical composition, structure, mechanical properties and thermal stability are discussed in detail. All coatings exhibit smooth surface without obvious elemental segregation and the columnar structure tends to densify with increasing bias. The coatings possess a nanocomposite structure of amorphous-nanocrystalline silicides, in agreement with the results calculated based on three phase prediction parameters (ΔH mix : enthalpy of mixing, δ: atomic size difference and Ω: ratio of entropy of mixing ΔS mix to ΔH mix). The coating deposited at bias of − 50 V presents optimal mechanical properties with nanohardness of ∼15.2 GPa, scratch crack propagation resistance of 1042 N2 and wear rate of 5.4 × 10−8 mm3N−1m−1. Annealing treatment further unravels that the presence of hard silicides is the hardening mechanism of coatings with super-hardness of ∼24 GPa. The results indicate that the AlCrNbSiTi coating is a promising protective coating with broad industrial application prospects. • Structure of coatings is a nanocomposite of amorphous-nanocrystalline silicides. • Annealing unravels hardening mechanism of coatings is presence of hard silicides. • Coating deposited at − 50 V exhibits a super-hardness of 24 GPa after annealing. • Wear mechanism of coatings is revealed with a lowest wear rate of 5.4 × 10−8 mm3/Nm. [ABSTRACT FROM AUTHOR]

Degenerate semiconductor is very highly desired in energy conversion and storage technologies due to its metal-like conduction behaviors. This is the first time the doping S 2 in Ni 3 S 2 lattice into chemically homogeneous Ni 3 (S) 1.1 (S 2) 0.9 superlattice structure is proposed to induce a degenerate characteristic towards excellent electrical conductivity and high-rate capability. In this study, a series of the chemically homogeneous S 2 -doped Ni 3 (S) 1.8 (S 2) 0.2 , Ni 3 (S) 1.6 (S 2) 0.4 , Ni 3 (S) 1.3 (S 2) 0.7 , and Ni 3 (S) 1.1 (S 2) 0.9 micropyramid arrays on Ni foam were synthesized by reacting the Ni foam and alkaline sulfur aqueous solution in different S 2 2- concentrations. The perfect Ni 3 (S) 1.1 (S 2) 0.9 superlattice structure corresponds to the periodic S–Ni–S 2 atom arrangements in whole crystal lattice, which endows a degenerate characteristic of metal-like electrical conductivity to significantly improve the electrochemical performance. The bulk series resistance (R s) value is only 0.62 Ω, while the charge-transfer resistance (R ct) is nearly 0 Ω in the superlattice Ni 3 (S) 1.1 (S 2) 0.9 electrode. As a cathode material for application in lithium ion batteries (LIBs), a very high specific capacity of 874 mAh g−1 is achieved at current density of 200 mA g−1. Remarkably, it still holds a high capacity of 565 mAh g−1 at current density of 500 mA g−1, indicating its superior high-rate capability. This study reveals that the periodic S–Ni–S 2 atom arrangements in crystal lattice is a key factor in determining the superlattice structure, high specific capacity, and the dynamic behaviors of electron/ion transport. Degenerate doping S 2 in Ni 3 S 2 lattice into chemically homogeneous superlattice Ni 3 (S) 1.1 (S 2) 0.9 multi-storey micropyramids array on Ni foam towards excellent electrical conductivity and high-rate capability. Image 1 [ABSTRACT FROM AUTHOR]