Numerical simulation of solar cells besed CZTS buffer layer (ZnO1-XSX) using SCAPS-1D software

Cds buffer layer has many advantages such as large bandgap, and the carrier density. Otherwise, the presence of cadmium is an inconvenient. Research work, are shifted on the possibility of replacing CdS by a buffer layer devoid of cadmium. This manuscript presents the numerical study, using SCAPS-1D program, the effects of sulfur content in the buffer layer Zn (O,S) on the electrical parameters of the solar cell ZnO: Al / i-ZnO / Zn (O, S) / CZTS /. Changes in the band gap and electron affinity of Zn (O, S) were calculated from the law of Vegard. The numerical results of the thickness of the absorbent layer CZTS equal to 2.5μm, show that from the sulfur content equals to 45% we can find the same results with CdS, an efficiency varies slightly, about 19%.Keywords: CZTS; ZnO1-xSx; CdS; SCAPS; Solar cell

A Raman study of single crystal congruent lithium niobate following electric field repoling

We describe a study of the time dynamics of the spectral position of six major peaks in the Raman spectrum of single-crystal congruent lithium niobate, following the process of electric-field repoling. All of the peaks observed show a small (&lt;1 cm-1) frequency shift after repoling. Two peaks are shifted to higher frequencies while the other four are shifted to lower frequencies. The shift generally recovers over time towards the original value. The 153 cm-1 and 432 cm-1 peaks are seen to recover to their original positions before poling, with time constants of approximately 8 h and 4 h, respectively, whereas the higher frequency peak at 872 cm-1 does not appear to recover at all. The other peaks exhibit incomplete recovery. We compare the measured values of temporal recovery with published relaxation times for internal electric fields, and make an additional comparison with our measured etch-rate data for the -z face of lithium niobate as a function of delay time following repoling. <br/

Analytical and experimental study of pressure dynamics in a pulsed water jet device

Pulsed high-velocity water jets are of interest for breaking rocks and other materials. This paper describes a straightforward way of generating single water pulse with a hammer impacting a piston that rests on top of a chamber filled with water. This impacting action pressurises the water, expelling it at high velocity through a nozzle. A theoretical investigation is outlined aimed at gaining a better understanding of this system for generating water pulses. A computational model is developed to simulate the pressure dynamics in the chamber based on continuity and momentum equations for a compressible viscous flow. This model is used to optimise the relative sizes of the hammer and piston as well as the height of the water column to produce the highest velocity water pulse. The model was validated by building an experimental apparatus. In these experiments maximum pressures of about 200 MPa were measured inside the chamber over a time period of about 560 μs. This produced a water pulse with maximum velocity of 600 m/s. Experiments were conducted with nozzle diameters between about 1 mm and 4 mm to study the effect of discharge volume on the pressure history. The results illustrate that although the peak attainable pressure decreases with an increase in nozzle diameter, the duration of the elevated pressure remains similar for all nozzles