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Inorganic cesium lead iodide perovskite CsPbI3 is attracting great attention as a light absorber for single or multi‐junction photovoltaics due to its outstanding thermal stability and proper band gap. However, the device performance of CsPbI3‐based perovskite solar cells (PSCs) is limited by the unsatisfactory crystal quality and thus severe non‐radiative recombination. Here, vacuum‐assisted thermal annealing (VATA) is demonstrated as an effective approach for controlling the morphology and crystallinity of the CsPbI3 perovskite films formed from the precursors of PbI2, CsI, and dimethylammonium iodide (DMAI). By this method, a large‐area and high‐quality CsPbI3 film is obtained, exhibiting a much reduced trap‐state density with prolonged charge lifetime. Consequently, the solar cell efficiency is raised from 17.26 to 20.06 %, along with enhanced stability. The VATA would be an effective approach for fabricating high‐performance thin‐film CsPbI3 perovskite optoelectronics. [ABSTRACT FROM AUTHOR]

Abstract: GaN films were deposited by hydride vapor phase epitaxy with and without adopting growth interruption modulation (GIM). The surface morphologies of these samples were observed by atomic force microscopy. After chemical etching, the surface morphology of GaN film grown directly on sapphire changed greatly and turned out to be N-polarity, which could be changed into Ga-polarity when growing via interruption modulation. Photoluminescence spectra showed that optical property of Ga-polar film was better than that of N-polar film. High resolution X-ray diffraction revealed the high crystalline quality GaN film grown by using the GIM method. The polarity conversion was the result of surface reconstruction when adopting GIM method. [Copyright &y& Elsevier]

Porous templates were fabricated by hydrogen-etching metal organic chemical vapor deposited gallium nitride (GaN); these templates were used as substrates for the growth of GaN via hydride vapor phase epitaxy. The influence of annealing porous templates on GaN growth behavior was investigated. GaN epitaxied on the unannealing porous template followed the Volmer–Weber mode with the void preserved at the growth plane, whereas the GaN film on the annealed porous templates exhibited a layer-by-layer growth and filled the porous material. The GaN crystal quality was characterized by high-resolution XRD and CL, the results indicated that GaN grown with pores preserved at the template interface had a lower dislocation density than that grown with pores filled, and the best GaN film had a TD density of 10 4 cm −2 . [ABSTRACT FROM AUTHOR]

• Bilayer WS 2 was achieved by simple spin-coating and finely controlling the time of introducing sulfur. • The as-grown bilayer WS 2 exhibits good crystallinity with AA stacking. • Photodetector based on the bilayer WS 2 shows good performance. WS 2 is a promising material in the next generation integrated circuit applications and its electrical and optoelectronic characteristics is dependent on the number of layers. Here, a simple and scalable synthesis of WS 2 bilayers via chemical vapor deposition (CVD) is demonstrated by finely controlling the time of introducing sulfur. The optical and microstructural characterization of the as-grown bilayer WS 2 show a uniform single crystal quality. The photodetector based on bilayers WS 2 exhibits relatively good performance. [ABSTRACT FROM AUTHOR]

Abstract: Hexagonal single-crystal graphene domains were grown on copper (Cu) foil via chemical vapor deposition and were etched with hydrogen at 950°C from 7 to 60min at atmospheric pressure. Numerous trenches were observed on the initial graphene domains after etching, and the trench patterns were closely associated with the Cu crystal orientation. No trenches were found if the etching process was conducted before cooling down. Thus, the etching trenches were bound up with the wrinkles formed during the cooling down process. Then, the process of etching on the wrinkles was examined. This simple hydrogen etching technology proved that wrinkles and point defects existed even in hexagonal single-crystal graphene domains. This method could be a convenient way to detect the distribution and morphology of wrinkles in graphene. [Copyright &y& Elsevier]

Abstract: In this paper, the synthesis of high quality graphene on single-crystal Mo(110) films by chemical vapor deposition (CVD) of methane was reported for the first time. X-ray diffraction proves that carbon species had dissolved into the metal. The micro-Raman spectroscopy indicates that the thickness of Mo films, cooling rate and growing time play significant roles in the quality of as-grown graphene films. By optimizing the growth time (15min) and cooling rate (10°C/s), we achieved high quality graphene films with the small ratio I G/I 2D≈0.26 and the FWHM(2D)≈30.4cm−1 on 200nm-thick Mo films. Our experiments also suggest that graphene growth on Mo is a dissolution and segregation process as Ni. [Copyright &y& Elsevier]

• A simple synthesis method of scalable adlayer-free monolayer graphene on CuNi foil. • Graphene grown on Cu 80 Ni 20 has the advantage of much wider growth window than Cu. • Proposing a growth model of adlayer-free monolayer on Cu 80 Ni 20 substrate. Homogeneity is crucial to material applications. Although monolayer graphene was successfully prepared more than a decade ago, to date, the growth of adlayer-free monolayer with a large area remains challenging. Here, we report the synthesis of metre-size adlayer-free monolayer graphene film on Cu 80 Ni 20 foil via atmospheric pressure chemical vapour deposition. Experimental results show that the growth parameter window of adlayer-free monolayer graphene on Cu 80 Ni 20 is very wide, which makes the growth of adlayer-free monolayer graphene easy and controllable. A growth model of adlayer-free monolayer graphene on Cu 80 Ni 20 substrate is also proposed. [ABSTRACT FROM AUTHOR]

• Cu 2 S derived from the Cu-foam was used as the self-template of the 3D structures. • MoS 2 /Cu 2 S hybrids were prepared by one-step hydrothermal method. • The MoS 2 nanosheets were vertically aligned on the surface of Cu 2 S networks. • The hybrid materials improved the HER catalysts relative to pure MoS 2 or 3D Cu 2 S. Recent studies proved that MoS 2 is a promising noble metal-free electrocatalyst for hydrogen evolution reaction. Here, we report the three-dimensional (3D) structures of MoS 2 /Cu 2 S hybrids were prepared by a one-step hydrothermal method using copper foam. Cu 2 S derived from the copper foam was used as the self-template of the 3D structures. The MoS 2 nanosheet arrays were vertically aligned on the surface of Cu 2 S networks. The MoS 2 nanosheets on the 3D Cu 2 S structure maximized the exposure of their edge sites at the atomic scale and presented superior catalysis activity for hydrogen production. The ease of composite fabrication suggested that the MoS 2 /Cu 2 S composite is a promising candidate electrode material for hydrogen evolution. [ABSTRACT FROM AUTHOR]