PEROVSKI SOLAR CELLS WITH HIGH POWER CONVERSION EFFICIENCY

The experimental results obtained by applying PEDOT-PSS as a hole transport layer and PC61BM as a electron transport layer in perovskite solar cells with inverted planar architecture are presented in the work. These devices have reached a maximum power conversion efficiency (PCE) of about 19.27%. Solar cells in which bulk heterojunction was prepared from perovskite (CH3NH3PbI3) doped with PC61BM have registered a maximum PCE of approximately 23.59 %.</span

Heavy noble gas (Kr, Xe) irradiated (111)InP nanoporous honeycomb membranes with enhanced ultrafast all-optical terahertz emission

Nanoporous honeycomb membranes on InP (111) surfaces emit ultrafast coherent terahertz pulses under near-infrared optical excitation. Irradiating the membranes with heavy noble gas Kr or Xe ions enhances the terahertz emission. The emission does not vary with in-plane magnetic field rotation and exhibits three-cycle dependence on azimuthal-angle rotation. Both suggest the terahertz source is not transient currents but optical rectification enhanced by the heavy-ion irradiation

Preface : Thermophysical Aspects of Functional Materials and Surfaces (TAFCS)

PostprintPeer reviewe

Core–Shell GaAs-Fe Nanowire Arrays: Fabrication Using Electrochemical Etching and Deposition and Study of Their Magnetic Properties

The preparation of GaAs nanowire templates with the cost-effective electrochemical etching of (001) and (111)B GaAs substrates in a 1 M HNO3 electrolyte is reported. The electrochemical etching resulted in the obtaining of GaAs nanowires with both perpendicular and parallel orientations with respect to the wafer surface. Core–shell GaAs-Fe nanowire arrays have been prepared by galvanostatic Fe deposition into these templates. The fabricated arrays have been investigated by means of scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). The magnetic properties of the polycrystalline Fe nanotubes constituting the shells of the cylindrical structures, such as the saturation and remanence moment, squareness ratio, and coercivity, were analyzed in relation to previously reported data on ferromagnetic nanowires and nanotubes

Magnetic Properties of GaAs/NiFe Coaxial Core-Shell Structures

Uniform nanogranular NiFe layers with Ni contents of 65%, 80%, and 100% have been electroplated in the potentiostatic deposition mode on both planar substrates and arrays of nanowires prepared by the anodization of GaAs substrates. The fabricated planar and coaxial core-shell ferromagnetic structures have been investigated by means of scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). To determine the perspectives for applications, a comparative analysis of magnetic properties, in terms of the saturation and remanence moment, the squareness ratio, and the coercivity, was performed for structures with different Ni contents

Core–Shell Structures Prepared by Atomic Layer Deposition on GaAs Nanowires

GaAs nanowire arrays have been prepared by anodization of GaAs substrates. The nanowires produced on (111)B GaAs substrates were found to be oriented predominantly perpendicular to the substrate surface. The prepared nanowire arrays have been coated with thin ZnO or TiO2 layers by means of thermal atomic layer deposition (ALD), thus coaxial core–shell hybrid structures are being fabricated. The hybrid structures have been characterized by scanning electron microscopy (SEM) for the morphology investigations, by Energy Dispersive X-ray (EDX) and X-ray diffraction (XRD) analysis for the composition and crystal structure assessment, and by photoluminescence (PL) spectroscopy for obtaining an insight on emission polarization related to different recombination channels in the prepared core–shell structures

Electrochemical nanostructuring of (111) oriented GaAs crystals: From porous structures to nanowires

A comparative study of the anodization processes occurring at the GaAs(111)A and GaAs(111)B surfaces exposed to electrochemical etching in neutral NaCl and acidic HNO3 aqueous electrolytes is performed in galvanostatic and potentiostatic anodization modes. Anodization in NaCl electrolytes was found to result in the formation of porous structures with porosity controlled either by current under the galvanostatic anodization, or by the potential under the potentiostatic anodization. Possibilities to produce multilayer porous structures are demonstrated. At the same time, one-step anodization in a HNO3 electrolyte is shown to lead to the formation of GaAs triangular shape nanowires with high aspect ratio (400 nm in diameter and 100 μm in length). The new data are compared to those previously obtained through anodizing GaAs(100) wafers in alkaline KOH electrolyte. An IR photodetector based on the GaAs nanowires is demonstrated. © 2020 Monaico et al

Highly Porous and Ultra-Lightweight Aero-Ga2O3: Enhancement of Photocatalytic Activity by Noble Metals

A new type of photocatalyst is proposed on the basis of aero-β-Ga2O3, which is a material constructed from a network of interconnected tetrapods with arms in the form of microtubes with nanometric walls. The aero-Ga2O3 material is obtained by annealing of aero-GaN fabricated by epitaxial growth on ZnO microtetrapods. The hybrid structures composed of aero-Ga2O3 functionalized with Au or Pt nanodots were tested for the photocatalytic degradation of methylene blue dye under UV or visible light illumination. The functionalization of aero-Ga2O3 with noble metals results in the enhancement of the photocatalytic performances of bare material, reaching the performances inherent to ZnO while gaining the advantage of the increased chemical stability. The mechanisms of enhancement of the photocatalytic properties by activating aero-Ga2O3 with noble metals are discussed to elucidate their potential for environmental applications

Modulation of Electrical Conductivity and Lattice Distortions in Burolk HVPE-Gwn GaN

The nature of self-organized three-dimensional structured architectures with spatially modulated electrical conductivity emerging in the process of hydride vapor phase epitaxial growth of single crystalline n-GaN wafers is revealed by photoelectrochemical etching. The amplitude of the carrier concentration modulation throughout the sample is derived from photoluminescence analysis and the localized heterogeneous piezoelectric response is demonstrated. The formation of such architectures is rationalized based on the generation of V-shaped pits and their subsequent overgrowth in variable direction. Detailed structure analysis with respect to X-ray diffraction and transmission electron microscopy gives striking evidence for inelastic strain to manifest in distortions of the P63mc wurtzite-type structure. The deviation from hexagonal symmetry by angular distortions of the β angle between the basal plane and c-axis is found to be of around 1°. It is concluded that the lattice distortions are generated by the misfit strains originating during crystal growth, which are slightly relaxed upon photoelectrochemical etching