Two-Dimensional Halide Pb-Perovskite-Double Perovskite Epitaxial Heterostructures

Area of Science:

• Materials Science
• Solid-State Chemistry
• Nanotechnology

Background:

• Two-dimensional (2D) halide perovskites are promising for optoelectronics but face stability issues with lead (Pb) and tin (Sn).
• Pb-free halide double perovskites offer enhanced stability and chemical variety but haven't been integrated into epitaxial heterostructures.
• Epitaxial heterostructures are crucial for understanding and utilizing novel material properties.

Purpose of the Study:

• To develop and characterize epitaxial core-shell heterostructures using Pb-free double perovskites and 2D Pb perovskites.
• To investigate the structural orientation and stability of these novel heterostructures.
• To compare halide anion diffusion in Pb-free versus Pb-based perovskite heterostructures.

Main Methods:

• Epitaxial growth of Pb-free double perovskite shells (Ag-Bi, Ag-Sb, Ag-In, Na-Bi, Na-Sb, Na-In) around 2D Pb perovskite cores.
• Electron diffraction for in-depth structural analysis of heterostructure orientation.
• Thermal analysis to study anionic interdiffusion across interfaces.

Main Results:

• Successful formation of epitaxial core-shell heterostructures with Pb-free shells grown at 45° on Pb perovskite (100) surfaces.
• Structural analysis confirmed Pb-free shell growth along the [110] direction of the Pb perovskite core, attributed to lower surface energy.
• Halide anion diffusion was significantly suppressed in Pb-free perovskite heterostructures compared to Pb-based ones.

Conclusions:

• Pb-free double perovskite heterostructures exhibit unique structural properties and enhanced stability.
• The suppressed halide diffusion in these structures is advantageous for device longevity.
• These findings pave the way for future applications in advanced electronic and optoelectronic devices.