Numerical Simulation of Tandem Using ZnS as a Buffer Layer Cu I_(1-x)Ca_xSe₂/CuGaSe₂

In the global context of diversification of usable energy sources, the use of renewable energies, in particular solar photovoltaic energy, is becoming increasingly important. As such, the development of a new generation of photovoltaic cells based on the CIGS material is promising. Indeed, the efficiency of these cells has exceeded 20% in recent years. Thus, our work consists in the modeling of a tandem solar cell based on Cu(In,Ga)Se2 (CGS/CIGS). The goal is to optimize its physical and geometrical parameters in order to obtain a better photovoltaic conversion efficiency compared to other research works on tandem in the past. We used AMPS-1D software for the simulation. When we realize the tandem, the least efficient cell (CGS) imposes the current and the shape of the J-V characteristic of the tandem. We obtained a theoretical efficiency of 39.30% which is significantly higher than the efficiencies obtained in the past by other researchers with a short circuit current of 34.60 mA/cm2, an open circuit voltage of 1.74 V and a form factor of 65.20%. The simulation also showed that the high defect density in the material strongly impacts the performance of the tandem.