Possible improvement of solar cell efficiency

In this work we present the development of a new solar cell prototype in order to improve photovoltaic efficiency. In this model we show that the material can have three successive incident ray absorptions instead of two currently, by varying the incidence angle, the aperture between the summit of two neighbouring pyramids and their height. This study concerns in particular the photovoltaic parameters such as the spectral response. This model was checked for angles varying between 54 and 60° and for pyramid heights between 5 and 10 μm. For these values of incidence angle, the apertures between the summits of two neighbouring pyramids varied respectively from 14.54 to 11.54 μm for a pyramid height of 10 μm.     

Synthesis,X-ray structure and theoretical study of benzazole thioether and its zinc complex as corrosion inhibitors for steel in acidic medium

A ligand, 2-((benzo[d]thiazol-2-ylthio)methyl)-1H-benzo[d]imidazole, and its zinc complex have been synthesized. The structure of these compounds have been determined by spectroscopic techniques and single crystal X-ray diffraction. The corrosion inhibition study of these compounds for steel in 0.5 M H₂SO₄ medium has also been investigated using potentiodynamic polarization and EIS techniques. The quantum calculations were applied to investigate the relationship between the electronic properties and the corrosion inhibition efficiency of the two benzazoles derivatives. Surface analysis (XRF) indicated that the rust layer formed on the Cu-containing steels was enriched with Cu compounds. Polarization curves revealed that both inhibitors acted as a mixed-type inhibitor.     

Carbon analysis in CdTe by nuclear activation

We describe the capabilities of the nuclear reaction the measurement of absolute concentrations of C in CdTe by the charged particle activation (CPA) method. This technique is used to determine the segregation coefficient of C introduced as an impurity in CdTe.     

Fluorescent 2-(2′-hydroxybenzofuran)benzoxazole (HBBO) borate complexes: synthesis,optical properties,and theoretical calculations

The multi-step synthesis, structural and optical properties of original luminescent borate complexes derived from 2-(2′-hydroxybenzofuran)benzoxazole (HBBO) are reported. Functionalization at position 3 of the benzofuran ring was readily achieved through an electrophilic cyclization key step followed by a Sonogashira cross-coupling reaction. The optical properties of the resulting boron difluoride dyes highlight different photophysical behaviors depending on the nature of the substitution at position 3 of the benzofuran core (^tBu-phenylacetylene or NⁿBu₂-phenylacetylene). The NⁿBu₂-phenylacetylene moiety favors a sizeable intramolecular charge transfer as evidenced by a strong solvatochromism; a feature further confirmed by ab initio calculations.     

Effect of the growth conditions on the structural properties of CuInSe2 thin films obtained by the technique of close spaced vapor transport

Thin films of polycrystalline CuInSe₂ were deposited on Pyrex substrates using a simple system of close spaced vapor transport (CSVT). The used CSVT system is an open horizontal reactor, this does not require vacuum, a gas flow is enough. During the growth phase, the CSVT system is continuously crossed by argon gas. A study on the influence of the source temperature and the deposition duration on the structural properties of the deposited films is reported. Analyses by X-ray diffraction have shown that these films are polycrystalline and have a chalcopyrite structure. The preferential orientation of the (112) plane was obtained for the films deposited at 550 ^°C. From the X-ray spectra we calculated the lattice parameters a and c, the ratio c/a was found to be close to 2. The characterization of the deposited films by an energy dispersion spectrometer (EDS) has shown that their chemical composition is quasistoichiometric with a ratio Cu/In varying from 0.96 to 1.10. Analysis with a scanning electron microscope (SEM) of the deposited films surface has shown that those slightly rich in indium present a more homogeneous morphology and smaller crystallites sizes than the films slightly rich in copper. The measurement of the photoconductivity of the prepared compound has allowed us to determine the value of its gap at room temperature. It was found to be close to 0.99 eV.     

Erratum to: Synthesis,X-ray structure and theoretical study of benzazole thioether and its zinc complex as corrosion inhibitors for steel in acidic medium

Research on Chemical Intermediates -     

Three-photon correlations in a strongly driven atom-cavity system

The quantum dynamics of a strongly driven, strongly coupled single-atom-cavity system is studied by evaluating time-dependent second- and third-order correlations of the emitted photons. The coherent energy exchange, first, between the atom and the cavity mode, and second, between the atom-cavity system and the driving laser, is observed. Three-photon detections show an asymmetry in time, a consequence of the breakdown of detailed balance. The results are in good agreement with theory and are a first step towards the control of a quantum trajectory at larger driving strength.     

Capture of Gaseous Iodine in Isoreticular Zirconium-Based UiO-n Metal-Organic Frameworks: Influence of Amino Functionalization,DFT Calculations,Raman and EPR Spectroscopic Investigation

A series of Zr-based UiO-n MOF materials (n=66, 67, 68) have been studied for iodine capture. Gaseous iodine adsorption was collected kinetically from a home-made set-up allowing the continuous measurement of iodine content trapped within UiO-n compounds, with organic functionalities (−H, −CH₃, −Cl, −Br, −(OH)₂, −NO₂, −NH₂, (−NH₂)₂, −CH₂ NH₂) by in-situ UV-Vis spectroscopy. This study emphasizes the role of the amino groups attached to the aromatic rings of the ligands connecting the {Zr₆O₄(OH)₄} brick. In particular, the preferential interaction of iodine with lone-pair groups, such as amino functions, has been experimentally observed and is also based on DFT calculations. Indeed, higher iodine contents were systematically measured for amino-functionalized UiO-66 or UiO-67, compared to the pristine material (up to 1211 mg/g for UiO-67-(NH₂)₂). However, DFT calculations revealed the highest computed interaction energies for alkylamine groups (−CH₂NH₂) in UiO-67 (−128.5 kJ/mol for the octahedral cavity), and pointed out the influence of this specific functionality compared with that of an aromatic amine. The encapsulation of iodine within the pore system of UiO-n materials and their amino-derivatives has been analyzed by UV-Vis and Raman spectroscopy. We showed that a systematic conversion of molecular iodine (I₂) species into anionic I⁻ ones, stabilized as I⁻⋅⋅⋅I₂ or I₃⁻ complexes within the MOF cavities, occurs when I₂@UiO-n samples are left in ambient light.