Study and Analytical Modeling of the Influence of Technological and Geometric Parameters on the Performance of Ga0.67In0.33P/GaAs/Ga0.70In0.30As Tri-junction Photovoltaic Solar Cells

Abstract

In the context of global energy consumption, the production of photovoltaic solar energy remains very low. One solution to this problem is to use multi-junction solar cells with high efficiency. Efforts are being made to increase the efficiency of solar cells and reduce their cost of production. In order to optimize the performance of multi-junction solar cells, this paper presents an analytical model allowing to study and model the influence of technological and geometric parameters on the performance of tri-junction solar cells Ga0.67In0.33P/GaAs/Ga0.70In0.30As. These parameters are the thickness, doping and Gap energy of the three sub-cells making up the tri-junction solar structure. The thicknesses and doping of the emitters (bases) of the sub-cells are varied and chosen in order to optimize the efficiency of the Trijunction Solar Cell (TJSC) Ga0.67In0.33P/GaAs/Ga0.70In0.30As. The one hand, the base doping (emitter) is selected so as to minimize the dark current and the other hand,to reduce the resistive losses in this region. As for the thickness, it is chosen so as to minimize the recombination phenomena. The simulation results show that for a given thickness, the sub-cell efficiencies have maximums which evolve with the increase in doping. If the doping of the base (or emitter) of the sub-cells increases, there follows a proportional increase in the efficiency. In addition, when the optimal doping and thickness of the bases (or emitters) are reached, above these, they can vary over a wide range without considerably modifying the efficiency of the solar cell. This point about the tolerance ranges is very important for the practical realization of Photovoltaic solar cell structures. These results also show that the optimal performance of the Tri-junction Solar Cell are obtained for the relatively low thicknesses of the bases (or emitters) (100nm-700nm) with high doping values (Nb = 8e + 18cm−3 ) et (Ne = 1019cm−3 ). These optimal thicknesses are smaller than the optical penetration depths and the diffusion lengths of GaInP, GaAs and GaInAs materials.