Design of a CH₃NH₃PbI₃/CsPbI₃-based bilayer solar cell using device simulation

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Perovskite solar cells (PSCs) show promise with lead-based absorbers reaching ~25.5% efficiency.
• Single-junction PSCs face limitations in maximizing light harvesting and charge extraction.
• Bilayer architectures offer a pathway to overcome single-junction limitations for enhanced photovoltaic performance.

Purpose of the Study:

• To investigate and optimize a perovskite-perovskite bilayer solar cell composed of CsPbI₃ and CH₃NH₃PbI₃.
• To analyze the impact of various device parameters on the overall efficiency of the bilayer PSC.
• To achieve a power conversion efficiency significantly higher than single-junction perovskite solar cells.

Main Methods:

• Utilized SCAPS-1D simulation software for efficiency analysis of the CsPbI₃/CH₃NH₃PbI₃ bilayer solar cell.
• Calibrated seven key parameters: electron/hole transport materials, bulk defect density, doping concentration, absorber thickness, front electrode work function, and interface defect density.
• Performed systematic optimization of these parameters to maximize the power conversion efficiency (PCE).

Main Results:

• Achieved an optimized power conversion efficiency (η) of 33.54% for the CsPbI₃/CH₃NH₃PbI₃ bilayer PSC.
• Obtained optimal photovoltaic parameters: open-circuit voltage (V_OC) = 1.34V, short-circuit current density (J_SC) = 27.45 mA/cm², and fill factor (FF) = 90.49%.
• The bilayer cell's efficiency is approximately double that of individual CsPbI₃ or CH₃NH₃PbI₃ single-junction PSCs.

Conclusions:

• The perovskite-perovskite bilayer architecture significantly enhances solar cell efficiency.
• Optimization of doping concentration and defect density in the narrow bandgap material (CH₃NH₃PbI₃) critically impacts overall device performance.
• This bilayer design presents a viable strategy for developing next-generation, high-efficiency perovskite solar cells.