Atomic-scale microstructure of metal halide perovskite

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• Hybrid organic-inorganic perovskites are promising for solar cells but lack detailed microscopic understanding.
• Atomic-resolution imaging is crucial for elucidating the properties of crystalline solar materials.

Purpose of the Study:

• To image formamidinium lead triiodide thin films at the atomic level using low-dose electron microscopy.
• To understand the microscopic properties, grain boundaries, interfaces, and defect structures in these perovskites.
• To explain the regenerative properties of perovskites by investigating beam-induced degradation.

Main Methods:

• Atomic-resolution scanning transmission electron microscopy (STEM) with low electron dose irradiation.
• Imaging of formamidinium lead triiodide [CH(NH₂)₂PbI₃] thin films.
• Analysis of beam-induced degradation and defect structures.

Main Results:

• Revealed highly ordered atomic arrangements with sharp grain boundaries and coherent perovskite/PbI₂ interfaces.
• Observed absence of long-range disorder in the crystal structure.
• Found that electron beam irradiation causes loss of formamidinium ions, leading to lattice vacancies and explaining regenerative properties. Also observed aligned point defects and dislocations.

Conclusions:

• Provided atomic-level insights into the structure and degradation of lead halide perovskites.
• The findings clarify the relationship between microscopic structure, degradation, and regenerative properties in perovskite solar materials.
• This understanding is vital for the development of efficient and stable perovskite solar cells.