First-Principles Study of Anionic Diffusion in Two-Dimensional Lead Halide Perovskite Lateral Heterostructures

Area of Science:

• Materials Science
• Solid-State Physics
• Photovoltaics

Background:

• Perovskite heterostructures are promising for optoelectronics but suffer from poor stability due to halide anion interdiffusion.
• Surface modification with organic cations can mitigate ion diffusion, yet the underlying mechanisms in 2D lateral heterostructures are not fully understood.

Purpose of the Study:

• To investigate the ion migration mechanisms in 2D lead halide perovskite lateral heterostructures.
• To explore the influence of different interface defects and organic cations on ion mobility.
• To provide theoretical insights into enhancing the stability of perovskite-based devices.

Main Methods:

• First-principles calculations were employed to simulate ion migration pathways and energy barriers.
• Analysis focused on the migration of iodine and bromine anions across interfaces in heterostructures with varying cations.
• The effects of different interface defects (e.g., single bromine vacancy, single iodine defect) were systematically studied.

Main Results:

• Iodine atom migration is more favorable than bromine atom migration across the interface, irrespective of the cation.
• The lowest energy barrier for iodine migration occurs in the in-plane to out-of-plane direction.
• Organic cations significantly influence anion migration barriers; 345FAn promotes migration, while BA inhibits it.
• Interfacial single iodine defects lead to higher interdiffusion rates compared to single bromine vacancies.

Conclusions:

• The study elucidates the critical role of organic cations and interface defects in controlling ion migration in 2D perovskite heterostructures.
• Findings offer a deeper understanding of stability limitations and suggest strategies for designing more robust perovskite materials.
• The results provide valuable theoretical guidance for experimental efforts aimed at improving perovskite device performance and longevity.