Methylammonium Chloride as a Double-Edged Sword for Efficient and Stable Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Chemistry

Background:

• Additive engineering boosts perovskite solar cell (PSC) efficiency beyond 25%.
• However, additives can cause compositional heterogeneity and structural disorders in perovskite films.
• Understanding these detrimental effects is crucial for device performance.

Purpose of the Study:

• Investigate the dual effects of methylammonium chloride (MACl) on methylammonium lead mixed-halide perovskite (MAPbI3-xClx) films and PSCs.
• Analyze the impact of MACl-induced morphology transition on film quality and defect evolution.
• Develop a strategy to mitigate negative impacts and enhance PSC performance and stability.

Main Methods:

• Systematic investigation of MAPbI3-xClx film properties (morphology, optical, structural, defects) under MACl influence.
• Annealing process optimization to study morphology transition.
• Development and application of a FAX post-treatment strategy.
• Performance and stability testing of fabricated PSCs.

Main Results:

• MACl addition leads to undesirable morphology transitions during annealing, affecting film quality.
• The FAX post-treatment effectively inhibits morphology transition and suppresses defects.
• A champion power conversion efficiency (PCE) of 21.49% with a 1.17 V open-circuit voltage was achieved.
• The treated PSCs retained over 95% of their initial efficiency after 1200 hours of storage.

Conclusions:

• Additive-induced detrimental effects in halide perovskites must be understood for efficient and stable PSCs.
• The FAX post-treatment is a viable strategy to overcome MACl-induced issues.
• This work provides critical insights for designing high-performance and durable perovskite solar cells.