The development of a bilayer absorption scenario of CsPbI₃/Cs₂SnI₆ PSCs for enhanced efficiency and stability

The introduction of heterojunction structures in perovskite solar cells (PSCs) can lead to substantial enhancements in power conversion efficiency (PCE) and stability. Using the SCAPS-1D software, we have theoretically investigated the performance potential of CsPbI₃/Cs₂SnI₆ heterojunction PSCs. The purpose of incorporating a thin layer of Cs₂SnI₆ perovskite onto the CsPbI₃ layer is to enhance the stability of the device through the formation of a protective barrier that prevents the continuous degradation of CsPbI₃. The device's overall efficiency was found to be greatly enhanced by meticulously optimizing the acceptor concentration (N_A), defect density (N_t), and absorber thickness of CsPbI₃. In addition, the influence of various physical parameters such as the operating temperature, the work function of the metal rear contact, and series and shunt resistance on the photovoltaic performance of the device is comprehensively examined. With the systematic optimization of these parameters, the device exhibited improved performance and attained an outstanding PCE of 20.86 %, an open circuit voltage (V_OC) of 1.19 V, a fill factor (FF) of 81.77%, and a current density voltage (J_SC) of 21.32 mA/cm². We think that our work will provide theoretical guidance in the advancement of heterojunction devices with much improved efficiency and stability.