Exploring the potential of CsPbI₃/CsPbBr₃ heterojunction as an absorber layer in perovskite solar cells: a numerical and experimental study

Perovskite solar cells (PSCs) have gained popularity in recent times due to their high-power conversion efficiency (PCE) and cost-effective manufacturing. Heterojunction devices are emerging as an interesting topic for researchers. In this study, a comparison is made between the experimental performance and their numerical simulations using the solar cell capacitance simulator (SCAPS-1D) software of CsPbI₃/CsPbBr₃ perovskite bilayer and CsPbI₃ single-layer perovskite solar cell. It is evident from the experimental results that the incorporation of CsPbBr₃ layer enhances the PCE from 4.92 to 9.9% under solar illumination. Further, an ideally optimized device was made using SCAPS-1D by varying the thickness, defect density, back metal contact and temperature. The influence of series and shunt resistances (R_series and R_shunt) was theoretically investigated and discussed using the SCAPS-1D program to model the electrical characteristics of the cell as a function of active layer composition. Without these parasitic resistances, the results of the ideal device do not resemble the experimentally calculated values. By feeding the experimentally calculated R_series and R_shunt values to SCAPS-1D, we can analyse the primary constraints of the device’s current voltage characteristics. Ultimately, it is established that the heterojunction device can help in enhancing the performance of PSCs.