Etude des cellules solaires minces et ultraminces

Abstract

In this work, we have numerically studied two thin solar cells (even ultrathin) based on ZnO:Al/i-ZnO/ZnMgO/CZTS. We particularly focused on replacing the classic buffer layer at the CdS with the non-toxic and abundant ZnMgO material, in view of getting better performance. The influence of thickness, doping concentration and defect density of different layers of the two solar cells ZnO:Al/i-ZnO/ZnMgO/CZTS and ZnO:Al/i-ZnO/CdS/CZTS, as well as the interface defects density of ZnMgO/CZTS and CdS/CZTS, on the photovoltaic parameters of the cells studied was examined. Maintaining the optimal values of the different physical and geometrical parameters leading to the best efficiency, then we studied the influence of the gap energy Eg of the CZTS absorber layer and the RS and RSH resistances on the different photovoltaic parameters. The optimal efficiency corresponding to Eg  1.4 eV is 22.08 %, for the ZnMgO/CZTS cell and 23.64 % for the CdS/CZTS cell. Finally, a comparative study between our two cells was realized. The results have shown a large similarity of J-V characteristic and QE quantum efficiency. However, we note, the better performance of the ZnMgO/CZTS cell in the long wavelength region, the important region of the solar cell. Thus, it can be affirmed that ZnMgO would be a very good candidate to replace CdS considered until now as the most suitable material.