Wrap-Around Core-Shell Heterostructures of Layered Crystals

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Engineered heterostructures integrate dissimilar materials to create novel functionalities.
• Two primary classes of heterostructures exist: vertical van der Waals (vdW) stacks and laterally bonded 2D sheets.
• Thicker layered crystals can lead to complex geometries due to structural and topological conflicts.

Purpose of the Study:

• To investigate the spontaneous formation and properties of core-shell structures in layered tin chalcogenides.
• To explore the optoelectronic characteristics arising from unconventional, orthogonally layered interfaces.
• To assess the potential of these multifunctional structures for energy-conversion applications.

Main Methods:

• One-pot synthesis of layered tin chalcogenides to induce phase separation and core-shell formation.
• Characterization of the resulting orthorhombic SnS core and trigonal SnS2 shell structures.
• Measurement of optoelectronic properties, including carrier separation and light absorption.

Main Results:

• Spontaneous formation of core-shell structures with large orthorhombic SnS crystals enclosed by trigonal SnS2 shells.
• Coexistence of parallel vdW layering and unconventional, orthogonally layered core-shell interfaces.
• Anisotropic carrier separation observed near type II core-shell interfaces.
• Extended long-wavelength light harvesting demonstrated via spatially indirect interfacial absorption.

Conclusions:

• Multifunctional layered core-shell structures can be synthesized via phase separation in tin chalcogenides.
• The unique orthogonal interfaces facilitate anisotropic carrier separation and enhanced light absorption.
• These engineered heterostructures hold promise for advanced energy-conversion technologies.