Stabilizing black-phase formamidinium perovskite formation at room temperature and high humidity

The stabilization of black-phase formamidinium lead iodide (α-FAPbI3) perovskite under various environmental conditions is considered necessary for solar cells. However, challenges remain regarding the temperature sensitivity of α-FAPbI3 and the requirements for strict humidity control in its processing. Here we report the synthesis of stable α-FAPbI3, regardless of humidity and temperature, based on a vertically aligned lead iodide thin film grown from an ionic liquid, methylamine formate. The vertically grown structure has numerous nanometer-scale ion channels that facilitate the permeation of formamidinium iodide into the lead iodide thin films for fast and robust transformation to α-FAPbI3. A solar cell with a power-conversion efficiency of 24.1% was achieved. The unencapsulated cells retain 80 and 90% of their initial efficiencies for 500 hours at 85°C and continuous light stress, respectively.

Fabrication and characterization of Si1− x Ge x nanocrystals in as-grown and annealed structures: a comparative study

Multilayer structures comprising of SiO2/SiGe/SiO2 and containing SiGe nanoparticles were obtained by depositing SiO2 layers using reactive direct current magnetron sputtering (dcMS), whereas, Si and Ge were co-sputtered using dcMS and high-power impulse magnetron sputtering (HiPIMS). The as-grown structures subsequently underwent rapid thermal annealing (550–900 °C for 1 min) in N2 ambient atmosphere. The structures were investigated using X-ray diffraction, high-resolution transmission electron microscopy together with spectral photocurrent measurements, to explore structural changes and corresponding properties. It is observed that the employment of HiPIMS facilitates the formation of SiGe nanoparticles (2.1 ± 0.8 nm) in the as-grown structure, and that presence of such nanoparticles acts as a seed for heterogeneous nucleation, which upon annealing results in the periodically arranged columnar self-assembly of SiGe core–shell nanocrystals. An increase in photocurrent intensity by more than an order of magnitude was achieved by annealing. Furthermore, a detailed discussion is provided on strain development within the structures, the consequential interface characteristics and its effect on the photocurrent spectra.

Mouse intestinal organoid time-course experiments from single cells

Organoids recapitulate the self-organizing capacity of stem cells and the tissue organization of the original organ in a controlled and trackable environment. Intestinal organoids, in particular, can develop from a single cell into a fully-grown structure that contains most of the cell types, patterns, and morphogenetic properties of the adult intestine. Here we present a protocol for high-throughput organoid culture in multi-well plate format combined with high content immunofluorescence imaging and RNA extraction. Our protocol allows recording and analysis of thousands of organoids during several days of development.

SYNTHESIS OF HIGHLY STABLE SILVER-LOADED VERTICAL ZnO NANOWIRES ARRAY AND ITS ACETYLENE SENSING PROPERTIES

A silver-loaded one-dimensional (1D) vertical ZnO nanowires (NWs) array synthesized by a facile seed mediated hydrothermal-RF magnetron sputtering method has been investigated for the fabrication of a highly stable and reproducible acetylene (C2H2) gas sensor. Successful immobilization of silver nanoparticles (NPs) as a sensitizer on the ZnO NWs array significantly enhanced the C2H2 sensing properties and showed a stable sensing performance. The grown structure exhibited high response magnitude (30.8 at 1000[Formula: see text]ppm), short response time (43[Formula: see text]s) and excellent selectivity at 220[Formula: see text]C. The enhanced performance can probably be accounted for the effect of combining the highly orientated ZnO NWs and catalytically active silver-based network. The superior sensing features toward C2H2 along with broad detection range (1–1000[Formula: see text]ppm), outstanding stability and excellent reproducibility indicate that the sensor is a promising candidate for practical applications.

In-grown structure of NiFe mixed metal oxides and CNT hybrid catalysts for oxygen evolution reaction

The in-grown structure of oxides and CNT hybrids strongly favors the charge transfer at the interface leading to high electrochemical performance.

Electronic Structure and Magnetic State of TiSe2 Doped with Cr by Means of Intercalation or Substitution of Ti

Solid solutions 1T-CrxTi1-xSe2 (x = 0-0,83) were synthesized. Single crystals in the concentration range x = 0-0.69 were grown. Structure of these materials was studied on single- and polycrystalline samples. It was determined that chromium atoms substitute for titanium atoms in the TiSe2 host lattice. XPS measurements of the core levels together with the resonance valence band spectra of the 1T-CrxTi1-xSe2, as well as absorption spectra of Ti and Cr were performed. According to the experimental XAS data and multiplet atomic calculation, titanium and chromium atoms have oxidation numbers of +4 and +3, respectively. The local magnetic moment of about 3 eV is detected at Cr atoms. A transition into the spin glass state is observed. The modeling calculations of chromium local density of states were carried out. These results are in a good agreement with the experimental ones and suggest that 3d density of electronic states of chromium that substitutes for titanium in the host lattice is spin polarized and has a half-metallic character.

The study of HgCdTe MBE-grown structure with ion milling

Of many techniques used to characterize quality of HgCdTe, ion milling is emerging as a unique means to reveal electrically active and neutral defects and complexes. Ion milling is capable of strongly affecting electrical properties of HgCdTe, up to conductivity type conversion in p-type material. It appears, that strongly non-equilibrium processes which take place under ion milling, when material is oversaturated with mercury interstitial atoms generated near a surface, lead to formation of specific defect complexes, which may not form under other type of treatment. By measuring parameters of a crystal before and after milling, and following disintegration of defects with time after ion milling (’relaxation’), one can detect and identify these defects. This method was applied to analyse different samples grown by molecular beam epitaxy.

Superluminescence in Green Emission GaInN/GaN Quantum Well Structures under Pulsed Laser Excitation

We report nonlinear optical investigation of green emission GaInN/GaN multi-quantum structures grown along c- and m-axes on sapphire and bulk GaN substrates, respectively. Under intense pulsed photo excitation, we observed strong superluminescence near the lasing condition in c-plane grown quantum well structures with full width at half maximum of 6 nm. The superluminescence couples out of the edge of the sample in a mode pattern consistent with gain in a high mode of the waveguide. The wavelength of the superluminescence is 474 nm. The threshold intensity of superluminescence was found to be 156 kW/cm2. Increasing pump intensity leads to a strong photoluminescence blueshift as large as 380 meV in samples grown along the c-axis on sapphire substrate, while under the same excitation conditions, the blue shift for the m-axis grown structure on bulk GaN substrate is less than 10 meV. The large emission blueshift is hereby attributed to the internal piezoelectric field in the c-axis grown structure. We observe a gain value of 20 cm-1 together with internal absorption losses of 2.3 – 6.0 cm-1 for the superluminescent samples.