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The Cu 2 ZnSnS x Se 4−x (CZTSSe) thin film solar cells have attracted the attention of researchers due to it's earthabundant composition containing Copper, Zinc, Tin and Sulfur and Selenide with 12.6% record efficiency (2013-IBM). A 3D simulation analysis is presented here on the optical, electrical and thermal characteristics of CZTSSe solar cell using COMSOL Multiphysics 3D simulation package. COMSOL is capable of calculating the coupled optical-electrical-thermal models through Electromagnetic Wave, Semiconductor, and Heat Transfer modules for a finely meshed structure. Using this capability, we have calculated the optical photo-generation rate of the a Mo/Mo(S,Se) 2 /CZTSSe/CdS/ZnO/ITO/air structure by inserting the refractive index and extinction coefficient of every layer in Wave optic module in COMSOL. We also calculated the total optical generation rate for two structures with and without Mo(S,Se) 2 layer at the junction of Mo and CZTSSe layers. The current-voltage curve, electric field profile and the recombination rate of the cell has also been calculated by Semiconductor module coupled to wave optic module. The current-voltage characteristics shows an improvement in V oc for the cell with Mo(S,Se) 2 layer (0.46 V to 0.513 V) which was also suggested by IBM for a record cell efficiency. Finally, the thermal maps of the cell has been calculated by Heat Transfer Module coupled to Semiconductor module considering the Shockley-Read-Hall (SRH) recombination heat, Joule Heat and conductive heat flux. The total heat flux magnitude of the cell was also mapped as a result out of these heat generation and cooling sources. The SRH heat is maximum within the depletion width at the CZTSSe/CdS interface whereas the Joule heating is intensive at the Mo/Mo(S,Se) 2 /CZTSSe side. Interesting is to see that the heat is mainly conducted to environment from Mo side presented by the conductive heat map. The total heat flux is intensive at both top and bottom interfaces which means the heat is generated at both top and bottom sides of the cells and not only from the illuminated part.

Abstract-In this paper, we present a numerical model to study counter pulse propagation in semiconductor optical amplifiers. An improved finite-difference beam propagation method for solving the modified nonlinear Schrödinger equation is applied for the first time in the counterpropagation regime. In our model, group velocity dispersion, two-photon absorption, ultrafast nonlinear refraction, and the change in the gain peak wavelength with carrier density are included, which have not been considered simultaneously in previous counterpropagation models. The model is applied to demonstrate how a subpicosecond and picosecond probe pulse shape and spectrum can be modified by a counterpropagating pump pulse. Based on the results obtained by this model, while subpicosecond probe pulses can be compressed by in this scheme, their time-bandwidth product are also improved significantly. Furthermore, the effects of several parameters are analyzed to obtain the proper probe spectral peak shift using counterpropagating probe pulses. The accuracy and computational efficiency of the new scheme are assessed through numerical examples and are shown to be superior to previously published approaches.Index Terms-Counterpropagation, pulse shaping, semiconductor optical amplifier, ultrafast nonlinear effects.

According to our study, RIRS procedure in comparison with ESWL is a safe and successful option of treatment for renal pelvis stone of 10-20 mm in obese people.

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