New Families of Large Band Gap 2D Topological Insulators in Ethynyl-Derivative Functionalized Compounds

TL;DR

This paper reports the discovery of new 2D topological insulators with large band gaps, functionalized with ethynyl-derivatives, suitable for room and high-temperature applications, advancing the development of dissipationless electronic devices.

Contribution

The study introduces a new class of giant band gap 2D topological insulators based on ethynyl-derivative functionalized Pb and Bi compounds, demonstrating their topological properties through first-principles calculations.

Findings

Band gaps range from 0.79 eV to 0.99 eV.

Nanoribbons exhibit nontrivial topological order.

Chemical functionalization effectively tunes band gaps while preserving topology.

Abstract

The search for large band gap systems with dissipationless edge states is essential to developing materials that function under a wide range of temperatures. Two-dimensional (2D) topological insulators (TIs) have recently attracted significant attention due to their dissipationless transport, robust properties and excellent compatibility with device integration. However, a major barrier of 2D TIs is their small bulk band gap, which allows for applications only in extremely low temperatures. In this work, first principle calculations were used to analyze the geometric, electronic, and topological properties of PbC2X and BiC2X (X = H, Cl, F, Br, I) compounds. The band gap values are remarkably large, ranging from 0.79eV to 0.99eV. The nanoribbons of these compounds exhibited nontrivial topological order in the simulation, thus proving ethynyl-derivative functionalized Pb and Bi films to be new classes of giant band gap 2D TIs. In addition, these findings indicate that chemical functionalization with ethynyl-derivatives is an effective method to tune the band gap and preserve the nontrivial topological order. These novel materials that are applicable at both room temperature and high temperatures open the door to a new generation of electronics.