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In this work, we reported TEM observations of several CdS thin films prepared by close space submission, sputtering, chemical bath deposition and electronic deposition technologies. The CdS layers prepared by close space submission and sputtering methods had larger grains (50–80 nm), while the CdS layers deposited by chemical bath had very small grains with the size of 5–10 nm. Electro deposited CdS yielded more like an epitaxial film. The optical and chemical properties showed good quality of CdS films prepared by all methods. In this work we proposed a suitable CdS multilayer structure to use it as a window layer in thin film solar cells. [ABSTRACT FROM AUTHOR]

Abstract: CdS layers grown by chemical bath deposition (CBD) are treated in different ways to improve the performance of CdS/CdTe solar cells. It has been found that the open circuit voltage of the CdS/CdTe solar cell increases when the CBD CdS is annealed with CdCl2 before the deposition of CdTe by close spaced sublimation (CSS). A thin CBD CdS (∼80nm) with bi-layer structure can significantly improve the short circuit current of the CdS/CdTe solar cells. [ABSTRACT FROM AUTHOR]

Since the first successful exfoliation of graphene, the superior physical and chemical properties of two-dimensional (2D) materials, such as atomic thickness, strong in-plane bonding energy and weak inter-layer van der Waals (vdW) force have attracted wide attention. Meanwhile, there is a surge of interest in novel physics which is absent in bulk materials. Thus, vertical stacking of 2D materials could be critical to discover such physics and develop novel optoelectronic applications. Although vdW heterostructures have been grown by chemical vapor deposition, the available choices of materials for stacking is limited and the device yield is yet to be improved. Another approach to build vdW heterostructure relies on wet/dry transfer techniques like stacking Lego bricks. Although previous reviews have surveyed various wet transfer techniques, novel dry transfer techniques have been recently been demonstrated, featuring clean and sharp interfaces, which also gets rid of contamination, wrinkles, bubbles formed during wet transfer. This review summarizes the optimized dry transfer methods, which paves the way towards high-quality 2D material heterostructures with optimized interfaces. Such transfer techniques also lead to new physical phenomena while enable novel optoelectronic applications on artificial vdW heterostructures, which are discussed in the last part of this review. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) exhibit interesting electronic and optical properties depending on their complex layer stacking and unique architectures. Here, we develop a high-efficiency and low-cost chemical vapor deposition technique to controllably grow 2D MoSe2 flakes with kirigami structures. Optical microscopy, atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy were used to characterize the kirigami architectures. Similar kirigami structures can also be extended to WSe2 flakes. This work expands the chemical toolbox for design and fabrication of TMDCs and offers new opportunities for engineering 2D materials with unique three-dimensional architectures and complex layer stacking to develop novel electronic devices and catalysts. [ABSTRACT FROM AUTHOR]

In this work, we reported on the synthesis of atomically thick WSe 2 nanoribbons with straight edges and a maximum lateral size of 85 μm on SiO 2 /Si substrates via a one-step chemical vapour deposition. Optical microscope, atomic force microscope and X-ray photoelectron spectroscopy measurements were used to characterize the morphologies and chemical composition of the as-grown WSe 2 nanoribbons. Photoluminescence spectra and Raman spectra indicated that the interlayer coupling may be varied with different stacking manner. A vapour–liquid–solid mechanism was proposed to rationalize the formation of WSe 2 nanoribbons. Moreover, we showed that WSe 2 nanoribbons could also be grown on MoSe 2 flakes with the same approach, demonstrating the extendibility of this strategy. Our work provides an efficient method to obtain WSe 2 nanoribbons for novel application in catalysts and electronic devices. [Display omitted] • Epitaxial growth of atomically thick WSe 2 nanoribbons via a one-step CVD. • A 3R phase was observed at the corner of multilayer WSe 2 nanoribbons. • Epitaxial growth of WSe 2 nanoribbons on monolayer MoSe 2 substrates. • DFT calculations unravel that the edges of the WSe 2 nanoribbons are active sites. [ABSTRACT FROM AUTHOR]