Search results for "Note"
showing 10 items of 10709 documents
Tuning optical/electrical properties of 2D/3D perovskite by the inclusion of aromatic cation
2018
The employment of bulky aliphatic cations in the manufacture of moisture-stable materials has triggered the development and application of 2D/3D perovskites as sensitizers in moisture-stable solar cells. Although it is true that the moisture stability increases, it is also true that the photovoltaic performance of 2D/3D PVK materials is severely limited owing to quantum and dielectric confinement effects. Accordingly, it is necessary the synthesis and deep optical characterization of materials with an adequate management of dielectric contrast between the layers. Here, we demonstrate the successful tuning of dielectric confinement by the inclusion of a conjugated molecule, as a bulky cation…
Fabrication and Photoelectrochemical Behavior of Ordered CIGS Nanowire Arrays for Application in Solar Cells
2010
In this work, we report some preliminary results concerning the fabrication of quaternary copper, indium, gallium, and selenium CIGS nanowires that were grown inside the channels of an anodic alumina membrane by one-step potentiostatic deposition at different applied potentials and room temperature. A tunable nanowire composition was achieved through a manipulation of the applied potential and electrolyte composition. X-ray diffraction analysis showed that nanowires, whose chemical composition was determined by energy-dispersive spectroscopy analysis, were amorphous. A composition of Cu0.203In0.153Ga0.131Se0.513, very close to the stoichiometric value, was obtained. These nanostructures wer…
Optical Optimization of the TiO2 Mesoporous Layer in Perovskite Solar Cells by the Addition of SiO2 Nanoparticles
2018
In this work, SiO2 nanoparticles (NPs) were integrated into the mesoporous TiO2 layer of a perovskite solar cell to investigate their effect on cell performance. Different concentrations of SiO2/ethanol have been combined in TiO2/ethanol to prepare pastes for the fabrication of the mesoporous layer with which perovskite solar cells have been fabricated. Addition of SiO2 NPs of 50 and 100 nm sizes produces an enhancement of cell performance mainly because of an improvement of the photocurrent. This increment is in good agreement with the theoretical predictions based on light scattering induced by dielectric SiO2 NPs. The samples using modified scaffolds with NPs also present a significant l…
Growth of two-dimensional Au patches in graphene pores: A density-functional study
2017
Inspired by recent studies of various two-dimensional (2D) metals such as Au, Fe and Ag, we study the growth of two-dimensional gold patches in graphene pores by density-functional theory. We find that at room temperature gold atoms diffuse readily on top of both graphene and two-dimensional gold with energy barriers less than $0.5$ eV. Furthermore, gold atoms move without barriers from the top of graphene to its edge and from the top of 2D gold to its edge. The energy barriers are absent even at the interface of 2D gold and graphene, so that the gold atoms move effortlessly across the interface. We hope our demonstration for the propensity of diffusing gold atoms to grow 2D gold patches in…
Automatable sample fabrication process for pump-probe X-ray holographic imaging
2014
Soft X-ray holography is a recently developed imaging technique with sub-50 nm spatial resolution. Key advantages of this technique are magnetic and elemental sensitivity, compatibility with imaging at free electron laser facilities, and immunity to in-situ sample excitations and sample drift, which enables the reliable detection of relative changes between two images with a precision of a few nanometers. In X-ray holography, the main part of the experimental setup is integrated in the sample, which consequently requires a large number of fabrication steps. Here we present a generic design and an automatable fabrication process for samples suitable, and optimized for, efficient high resolut…
Coating Evaporated MAPI Thin Films with Organic Molecules: Improved Stability at High Temperature and Implementation in High-Efficiency Solar Cells
2018
Methylammonium lead iodide (MAPI) has proven to be an exceptional light-absorber for single-junction thin-film solar cells. Nonetheless, degradation induced by environmental agents (air, moisture, heat) limits the stability of this hybrid perovskite. Here, we demonstrate that coating evaporated MAPI thin films with different hydrophobic molecules leads to a significant improvement in their stability. We especially investigated the degradation of MAPI and the subsequent formation of PbI2 at 150 °C by in situ XRD analysis and showed that this transformation is remarkably slowed down in films coated with trioctyl phosphine oxide and tridodecyl methylammonium iodide. This enhances the processab…
Pulsed Laser Deposition of Cs 2 AgBiBr 6 : from Mechanochemically Synthesized Powders to Dry, Single-Step Deposition
2021
Cs2AgBiBr6 has been proposed as a promising lead-free and stable double perovskite alternative to hybrid and lead-based perovskites. However, the low solubility of precursors during wet synthesis, or the distinct volatility of components during evaporation, results in complex multistep synthesis approaches, hampering the widespread employment of Cs2AgBiBr6 films. Here, we present pulsed laser deposition of Cs2AgBiBr6 films as a dry, single-step and single-source deposition approach for high-quality film formation. Cs2AgBiBr6 powders were prepared by mechanochemical synthesis and pressed into a solid target maintaining phase purity. Controlled laser ablation of the double perovskite target i…
Evaluation of interlaminar delaminations in titanium-graphite fibre metal laminates by infrared NDT techniques
2018
Abstract Fibre Metal Laminates (FMLs) describe a number of aerospace-grade layered structural materials where thin metal alloy foils are interleaved with Fibre Reinforced Polymer (FRP) plies. Such material hybridisation at the layer meso-scale poses a challenge for non-destructive testing (NDT). On the other hand, the need for NDT inspection of FMLs arises due to the potential development of interlayers disbonds, both during fabrication or in-service. This work describes the successful implementation of two Infrared-NDT approaches to evaluate a defected FML panel made of Titanium/Graphite (Ti-Gr). One technique is based on the modulation of the deployed heat from a low-cost halogen lamp, to…
Diels-Alder Reactions of Tetraphenylcyclopentadienones in Nanochannels: Fabrication of Nanotubes from Hyperbranched Polyphenylenes
2005
A water-soluble hexa-peri-hexabenzocoronene: synthesis, self-assembly and role as template for porous silica with aligned nanochannels
2005
A water-soluble hexa-peri-hexabenzocoronene was prepared and shown to undergo ordered columnar self-assembly either in water solution or bulk and therefore served as template for the fabrication of porous silica with aligned nanochannels.