In this study, the authors fabricated high performance core–shell nanostructured flexible photodetectors on a polyimide substrate of Kapton. For this purpose, p-type copper indium gallium selenide (CIGS) nanorod arrays (core) were coated with aluminum doped zinc oxide (AZO) films (shell) at relatively high Ar gas pressures. CIGS nanorods were prepared by glancing angle deposition (GLAD) technique using radio frequency (RF) magnetron sputtering unit at room temperature. AZO films were deposited by RF sputtering at Ar pressures of 1.0×10−2 mbar (high pressure sputtering) for the shell and at 3.0×10−3 mbar (low pressure sputtering) to create a top contact. As a comparison, the authors also fabricated conventional planar thin film devices incorporating CIGS film of similar material loading to that of CIGS nanorods. The morphological characterization was carried out by field-emission scanning electron microscope. The photocurrent measurement was conducted under 1.5 AM sun at zero electrical biasing, where CIGS devices were observed to absorb in the ultraviolet-visible-near infrared spectrum. GLAD core–shell nanorod photodetectors were shown to demonstrate enhanced photoresponse with an average photocurrent density values of 4.4, 3.2, 2.5, 3.0, and 2.5 μA/cm2 for bending angles of 0°, 20°, 40°, 60°, and 80°, respectively. These results are significantly higher than the photocurrent of most of the flexible photodetectors reported in the literature. Moreover, our nanorod devices recovered their photoresponse after several bending experiments that indicate their enhanced mechanical durability. On the other hand, thin film devices did not show any notable photoresponse. Improved photocurrent of CIGS nanorod devices is believed to be due to their enhanced light trapping property and the reduced interelectrode distance because of the core–shell structure, which allows the efficient capture of the photo-generated carriers. In addition, enhanced mechanical durability is achieved by the GLAD nanorod microstructure on a flexible substrate. This approach can open a new strategy to boost the performance of flexible photodetectors and wearable electronics.

Fuel cell technology is one of the solutions which can play an important role in the environmentally friendly with more efficient, cleaner and quieter than traditional internal combustion engines. Among the fuel cells types polymer electrolyte membrane fuel cells have many advantages regarding quick start-up time, less warm-up time high power density and high efficiency. There are still some limitations due to the cost of Pt-based catalysts. Platinum based catalysts are presently the most promising catalysts for Oxygen Reduction Reaction (ORR) in Fuel Cells. Homogenously distributed Pt nanoparticles on carbon support (Pt/C) nanoparticles are mostly using in conventional way to produce Fuel Cells. Pt-based electrocatalysts with higher activity and durability are needed for cost-competitive PEM Fuel Cells. It can be developed/improved further by using Platinum-based/alloy thin film core-shell nanostructures. For this reason, this article reviewed the significance and processing of such core/shell structures. The general information about Fuel Cells is given at the beginning of this review article. Later, type of the fuel cells along with more definition of the PEM Fuel Cells are described. The Pt shell on Ni, Cr, Pd, Ru, and WC core nanorods increase the stability and durability and decrease the cost based on the published works. This nanostructured design will significantly impact the fuel cell technology by improving catalysts. Specifically, by controlling size, composition, and surface-area-to-volume ratios, this review article describes the investigation of the core/shell nanostructured array catalysts. A few of the following examples of core/shell structures and supported catalysts proved electrocatalytic oxygen reduction.

Cadmium sulfide (CdS) used in dye-sensitized solar cells (DSSCs) is currently mainly synthesized by chemical bath deposition, vacuum evaporation, spray deposition, chemical vapor deposition, electrochemical deposition, sol–gel, solvothermal, radio frequency sputtering, and hydrothermal process. In this paper, CdS was synthesized by hydrothermal process and used with a mixture of titanium dioxide anatase and rutile (TiO 2(A+R) ) to build the photoanode, whereas the counter electrode was made of nanocomposites of conductive polymer polyaniline (PANI) and multiwalled carbon nanotubes (MWCNTs) deposited on a fluorine-doped tin oxide substrate. Two morphologies of CdS have been obtained by using hydrothermal process: branched nanorods (CdS BR ) and straight nanorods (CdS NR ). The present work indicates that controlling the morphology of CdS is crucial to enhance the efficiency of DSSCs device. Indeed, the higher power conversion energy of 1.71% was achieved for a cell CdS BR –TiO 2(A+R) /PANI–MWCNTs under 100 mW/cm 2 , whereas the power conversion energy of 0.97 and 0.83% for CdS NR –TiO 2(A+R) /PANI–MWCNTs and TiO 2(A+R) /PANI–MWCNTs, respectively. Therefore, by increasing the surface to volume ratio of CdS nanostructures and the crystallite size into those structures opens the way to low-cost chemical production of solar cells.

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A critical factor for an efficient light harvesting device is reduced reflectance in order to achieve high optical absorptance. In this regard, refractive index engineering becomes important to minimize reflectance. In this study, a new fabrication approach to obtain density-modulated CuIn GaSe (CIGS) thin films with self-anti-reflective properties has been demonstrated. Density-modulated CIGS samples were fabricated by utilizing high pressure sputtering (HIPS) at Ar gas pressure of 2.75 × 10 mbar along with conventional low pressure sputtering (LPS) at Ar gas pressure of 3.0 × 10 mbar. LPS produces conventional high density thin films while HIPS produces low density thin films with approximate porosities of ∼15% due to a shadowing effect originating from the wide-spread angular atomic of HIPS. Higher pressure conditions lower the film density, which also leads to lower refractive index values. Density-modulated films that incorporate a HIPS layer at the side from which light enters demonstrate lower reflectance thus higher absorptance compared to conventional LPS films, although there is not any significant morphological difference between them. This result can be attributed to the self-anti-reflective property of the density-modulated samples, which was confirmed by the reduced refractive index calculated for HIPS layer via an envelope method. Therefore, HIPS, a simple and scalable approach, can provide enhanced optical absorptance in thin film materials and eliminate the need for conventional light trapping methods such as anti-reflective coatings of different materials or surface texturing.