The main objective of researches in the field of photovoltaic is to increase the efficiency. This work aims a new concept which is the integration of nanoparticles in the anti-reflection layerSi3N4 (silicon nitride), in order to improve the performance of solar cells. This concept is based on the up conversion, where the nanoparticles are characterized by the ability to function as a converter of infrared rays having high energies in the receptivity in the visible. The concept of conversion leads to a better exploitation of the solar spectrum, by widening the useful range of the spectrum. Firstly, we realized SiNx layers at different compositions and proved that variation by calculating the silicon excess and the gap energy. But the focus is on the analysis of photocurrent measurements for the vertical and lateral configuration to show the role of nanparticules. And we finalize with measurement of currents at the test bench I-V to find the ideal stoichiometry for nanoparticles.

The present study analyzes numerically the mixed thermosolutal convection in a vertical partly porous annular cavity. The fluid motion in the porous matrix is described by the generalized Darcy-Brinkman-Forchheimer model. The results show that the composite porous layer tends to improve the heat transfer and moderately reduce the transfer of aqueous solution compared to the case of a homogeneous porous partition. This conclusion is valid for all characteristic values (Da, ) or the flow modes set up in the porous matrix.

The mechanical engineering industry is always in the search of new hardfacing alloys which nowadays make it possible to solve considerable delicate problems of abrasive wear and corrosion. These alloys are heterogeneous materials and are generally composed of a ductile matrix and a significant proportion in hard phases (carbides, borides or silicides), which give a good wear resistance and corrosion. The following studies made on alloys containing Ni, rich in Silicon and tungsten. We noted that addition of these elements (Si and W) got interesting mechanical properties. The alloys that we chose for this study contain the elements C, B, Si, Cr and W with additions in Ti and Mo. The aim of this work is the characterisation of the various phases formed during solidification, to study chemical affinities in this system poly-constitutes and to make a correlation between the chemical composition, the conditions of development and the microstructures obtained.