Numerical simulation and optimization of all-inorganic P-type heterojunction CsPbIBr2/CsGeI3 perovskite solar cells

The development of perovskite solar cells (PSCs) for practical applications remains constrained by challenges in efficiency and stability. To address these limitations, a novel P-type heterojunction PSC was designed and optimized using SCAPS-1D. This fully inorganic device, which omits a hole transport layer, exhibits high stability. Its architecture combines CsPbIBr₂ as the primary absorber layer with CsGeI₃ as a secondary layer. The resulting built-in electric field enhances carrier transport and extends light absorption across the visible spectrum, improving overall photon utilization. By systematically varying absorber layer thickness, doping concentration, and defect density, the simulation examined their effects on light absorption, energy band bending, and SRH recombination rates. In addition, careful selection of the electron transport layer (ETL) and metal work functions further optimized device performance. The resulting PSC achieved a maximum power conversion efficiency (PCE) of 30.13 % with a fill factor (FF) of 85.14 % under ideal conditions, and retained a PCE of 26.63 % with an FF of 81.74 % under practical conditions, significantly surpassing single-layer PSC designs. These results demonstrate the potential of P-type heterojunction lead-germanium PSCs for optoelectronic applications and provide a theoretical framework for developing high-efficiency, stable, and cost-effective devices.