Phosphate-Passivated SnO₂ Electron Transport Layer for High-Performance Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Tin oxide (SnO2) is a common electron transport layer (ETL) in perovskite solar cells (PSCs).
• High surface trap density in SnO2 limits electron collection efficiency and overall PSC performance.
• Defects in ETLs hinder the development of efficient and stable perovskite solar cells.

Purpose of the Study:

• To mitigate surface defects in SnO2 ETLs using phosphoric acid.
• To enhance electron collection efficiency and improve the performance of perovskite solar cells.
• To investigate the impact of phosphate passivation on SnO2 electron mobility and PSC stability.

Main Methods:

• Treatment of SnO2 with phosphoric acid to passivate surface dangling bonds.
• Characterization of phosphorus bonding and defect reduction using spectroscopic analysis.
• Fabrication and performance testing of perovskite solar cells with modified SnO2 ETLs.

Main Results:

• Phosphoric acid treatment eliminated over 47.9% of Sn dangling bonds by forming chained phosphate groups.
• Optimized phosphoric acid concentration (7.4 atom %) increased electron mobility in SnO2 by approximately three times.
• Phosphate-passivated SnO2 ETLs led to a champion PSC with a power conversion efficiency (PCE) of 21.02%.

Conclusions:

• Phosphoric acid passivation is an effective strategy to reduce surface trap states in SnO2 ETLs.
• This simple method significantly improves electron mobility and enhances the power conversion efficiency of PSCs.
• The developed P-SnO2 ETL offers a pathway towards high-performance and potentially more stable perovskite solar cells.