Interface Defects and Recombination in HTL-Free and Bilayer Cs2SnI6 Perovskite Solar Cells: Numerical Modeling and...

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Perovskite solar cells (PSCs) are a leading sustainable energy technology.
• Lead-free Cs2SnI6 perovskites offer stability and environmental benefits for next-generation PSCs.

Purpose of the Study:

• To systematically investigate defect impacts on Cs2SnI6-based HTL-free and bilayer PSC architectures using SCAPS-1D simulations.
• To optimize device parameters and explore machine learning for performance prediction.

Main Methods:

• SCAPS-1D simulations were used to model HTL-free and bilayer Cs2SnI6 PSCs.
• Key parameters including defect densities and absorber thickness were optimized.
• Artificial Neural Networks (ANN), Random Forest (RF), and Multiple Linear Regression (MLR) models predicted device performance.

Main Results:

• Optimized HTL-free PSCs achieved a 27.92% power conversion efficiency (PCE).
• Optimized bilayer PSCs (with CsSnBr3) reached a 24.08% PCE.
• SHAP analysis identified defect density as critical for HTL-free devices and absorber thickness for bilayer devices.

Conclusions:

• An integrated simulation-machine learning framework effectively clarifies defect-driven performance.
• Practical guidance for interface optimization in lead-free PSCs was provided.
• This work highlights the potential of stable, lead-free PSCs for green energy applications.