Heterogeneous 2D/3D Tin-Halides Perovskite Solar Cells with Certified Conversion Efficiency Breaking 14

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Tin-halides perovskite solar cells are promising lead-free alternatives.
• Bulk defects, particularly tin oxidation (Sn2+ to Sn4+), limit their performance.
• Developing stable and efficient tin-based perovskites is crucial for next-generation solar technology.

Purpose of the Study:

• To develop a general and effective strategy to modulate the microstructure of 2D/3D heterogeneous tin-perovskite absorber films.
• To suppress tin oxidation and reduce defect density in FASnI3 perovskite solar cells.
• To enhance the device performance and stability of lead-free perovskite solar cells.

Main Methods:

• Substitution of formamidinium iodide (FAI) with phenethylammonium bromide (FPEABr) in FASnI3.
• Fabrication of 2D/3D heterogeneous tin-perovskite absorber films.
• Microstructural characterization to analyze the 2D phase embracing 3D grains at surfaces and grain boundaries.

Main Results:

• The introduction of a 2D phase induced highly oriented growth of the 3D FASnI3.
• The 2D/3D microstructure effectively suppressed Sn2+ to Sn4+ oxidation and decreased defect density.
• Device power conversion efficiency was remarkably enhanced from 9.38% to 14.81%, with a certified efficiency of 14.03%.

Conclusions:

• The developed 2D/3D heterogeneous microstructure strategy effectively enhances the stability and performance of tin-halides perovskite solar cells.
• The FPEA+-based 2D capping layer provides a reducing atmosphere, protecting the 3D FASnI3 grains.
• This work presents a new pathway for fabricating high-quality tin-perovskite absorber films, paving the way for efficient lead-free perovskite solar cells.