Carbohydrazide-Assisted Morphology and Structure Controlling for Lead-Free Cs₂AgBiBr₆ Double Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Inorganic Chemistry

Background:

• Metal halide perovskites face stability and toxicity challenges.
• Lead-free inorganic double perovskites like Cs₂AgBiBr₆ are promising alternatives.
• Poor film quality, often due to high annealing temperatures, limits Cs₂AgBiBr₆ photovoltaic performance.

Purpose of the Study:

• To develop a facile strategy for fabricating high-quality, pinhole-free Cs₂AgBiBr₆ films.
• To investigate the role of carbohydrazide (CBH) as an additive in improving film quality and photovoltaic performance.
• To enhance the stability and reproducibility of Cs₂AgBiBr₆-based devices.

Main Methods:

• Introduction of carbohydrazide (CBH) into the Cs₂AgBiBr₆ precursor solution.
• Fabrication of Cs₂AgBiBr₆ films and photovoltaic devices.
• Detailed characterization of film morphology, composition, and device performance.
• Long-term stability testing under ambient conditions.

Main Results:

• High-quality, pinhole-free Cs₂AgBiBr₆ films with large grain sizes were successfully fabricated using CBH.
• The carbonyl group (C═O) in CBH was identified as crucial for coordinating with Ag⁺ and Bi³⁺ cations, improving film formation.
• Optimized devices achieved a power conversion efficiency (PCE) of 1.57%, a 37% relative increase.
• The devices demonstrated excellent stability, retaining 95.0% of their initial performance after 1000 hours in ambient conditions.

Conclusions:

• Carbohydrazide (CBH) is an effective additive for improving the quality and performance of Cs₂AgBiBr₆ films.
• This additive engineering approach enhances device reproducibility and long-term stability.
• The findings facilitate the development of high-performance, lead-free perovskite solar cells and deepen the understanding of additive mechanisms.