First-principles study for a MXene terahertz detector

Abstract

2D transition metal carbides, nitrides, and carbonitides called MXenes have attracted increasing attention due to their outstanding properties in many fields. By performing systematic density functional theory calculations, here we show that MXenes can serve as excellent terahertz detecting materials. Giant optical absorptions and extinction coefficients are observed at the terahertz range in the most popular MXene, namely, Ti3C2, which is regardless of stacking degree. Various other optical properties are investigated as well at the terahertz range for in-depth understanding of its optical response. We find that the thermoelectric figure of merit (ZT) of stacked Ti3C2 flakes is comparable to that in carbon nanotube films. Based on excellent terahertz absorption and decent thermoelectric efficiency in MXenes, we finally suggest the promise of MXenes in terahertz detection applications, which includes terahertz bolometers and photothermoelectric detectors. Possible ZT improvements are discussed in largescale MXene flake films and/or MXene-polymer composite films.