Numerical Simulation of CsPbI₂Br‑based Hole‑transport‑layer‑free Heterojunction Solar Cells

In order to explore efficient and stable perovskite solar cells，the solar cell simulation software SCAPS-1D was used to design and study hole-transport-layer-free solar cells with CsPbI₂Br/CsPbI_2.5 Br_0.5 heterojunction as the absorption layer. Firstly，the single-absorption-layer CsPbI₂Br cells were studied，and then the cells with CsPbI₂Br/CsPbI_2.5Br_0.5 heterojunction as the absorption layer were constructed. The thickness，defect concentration and doping concentration of absorption layer and the interfacial defect concentration at SnO₂/CsPbI₂ Br interface were systematically studied and optimized for the heterojunction cell. The study found that the CsPbI₂Br/CsPbI_2.5Br_0.5 heterojunction could improve the energy level matching between the perovskite layer and the electrode，promote the separation and transport of carriers，and significantly increase the conversion efficiency of the cell. Through optimization，the structure obtained a highest simulation efficiency of 23.08%. These studies provide a theoretical reference for the fabrication of efficient hole-transport-layer-free CsPbI2 Br solar cells.