Topological Band Engineering of One-Dimensional π-d Conjugated Metal-Organic Frameworks

Area of Science:

• Materials Science
• Condensed Matter Physics
• Organic Chemistry

Background:

• One-dimensional (1D) conjugated metal-organic frameworks (c-MOFs) are crucial for energy applications.
• Understanding their electronic properties is key to advancing chemical energy storage and conversion.

Purpose of the Study:

• To introduce a universal principle for engineering topological bands in 1D c-MOFs.
• To experimentally verify the existence of topological bands in these materials.

Main Methods:

• Utilized first-principles calculations to investigate the electronic structure of Ni-based c-MOFs (NiQDI).
• Employed scanning tunneling microscopy (STM) to measure differential conductance spectra.
• Analyzed the formation of staggered hopping and topological bands driven by d orbitals and π orbitals.

Main Results:

• Discovered Su-Schrieffer-Heeger-shaped 1D topological bands in 1D c-MOFs.
• Identified spatially localized topological edge states at the NiQDI chain terminations.
• Confirmed the presence of these topological bands through STM measurements.

Conclusions:

• Provided conclusive experimental evidence for topological bands in 1D c-MOFs.
• Demonstrated a method to engineer topological bands by controlling orbital interactions.
• Paved the way for exploring topological physics in organic materials via frontier molecular orbitals.