Cation In Situ Exchange for Fabrication of CsSnI₃ Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Chemistry

Background:

• Inorganic CsSnI₃ perovskite solar cells (PSCs) show promise due to good optoelectronic properties and thermal stability.
• Fabricating high-quality CsSnI₃ films with low defects is challenging due to rapid crystallization and Sn(II) defects.

Purpose of the Study:

• To develop a novel cation in situ exchange strategy for fabricating high-quality CsSnI₃ perovskite films.
• To improve the performance and stability of CsSnI₃-based PSCs.

Main Methods:

• Employed a cation in situ exchange strategy using tin iodide (SnI₂), cesium formate (CsFa), and dimethylammonium iodide (DMAI) precursors.
• Formed DMASnI₃ intermediate, which transformed into black CsSnI₃ upon annealing, followed by removal of volatile byproducts.
• Characterized the CsSnI₃ film for coverage, crystallinity, and defect density.

Main Results:

• The cation exchange strategy yielded CsSnI₃ films with high coverage, improved crystallinity, and reduced defect density.
• The fabricated PSC achieved a power conversion efficiency (PCE) of 12.62%, significantly higher than the 6.82% of traditional devices.
• The optimized PSC demonstrated enhanced stability, retaining over 85% of its initial PCE after 30 days in a nitrogen environment.

Conclusions:

• The cation in situ exchange strategy is effective for producing high-quality CsSnI₃ films.
• This approach offers a viable pathway for realizing high-performance and stable tin-based halide perovskite solar cells.