Orientation-Controlled Large-Area Epitaxial PbI₂ Thin Films with Tunable Optical Properties

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Lead iodide (PbI₂) is a layered material with significant potential for optoelectronic applications.
• Previous research focused on micrometer-sized PbI₂ flakes, limiting scalability.
• Challenges exist in achieving large-area, well-oriented epitaxial thin films of PbI₂ and understanding their grain boundaries.

Purpose of the Study:

• To investigate the growth mechanism of large-area epitaxial PbI₂ thin films.
• To identify and characterize grain boundaries in these films.
• To understand the thermodynamic and kinetic factors influencing PbI₂ film growth.

Main Methods:

• Utilized mica as a model substrate for epitaxial growth of PbI₂ thin films.
• Employed mechanical exfoliation and physical vapor deposition techniques.
• Combined experimental observations with first-principles calculations.

Main Results:

• Demonstrated the synthesis of large-area epitaxial PbI₂ thin films on mica.
• Identified inversion domain boundaries due to partial growth and uncoalesced domains.
• Developed a comprehensive understanding of growth mechanisms, including thermodynamic and kinetic factors.

Conclusions:

• Established a method for reproducible synthesis of high-quality, large-area PbI₂ thin films with controlled orientation.
• The findings pave the way for fabricating PbI₂-based heterostructures on various substrates, including graphene.
• Opens new avenues for PbI₂ in optoelectronics, twistronics, and strain/substrate engineering.