Abstract-Dynamical Control over Terahertz Electromagnetic Interference Shielding with 2D Ti3C2Ty MXene by Ultrafast Optical Pulses

Guangjiang Li,  Naaman Amer,  Hassan A. Hafez, Shuohan Huang, Dmitry Turchinovich, Vadym N. Mochalin,  Frank A. Hegmann,  Lyubov V. Titova,

https://pubs.acs.org/doi/pdf/10.1021/acs.nanolett.9b04404 

High electrical conductivity and strong absorption of electromagnetic radiation in the terahertz (THz) frequency range by metallic 2D MXene Ti3C2Ty make it a promising material for electromagnetic interference shielding, THz detectors, and transparent conducting electrodes. Here, we demonstrate that ultrafast optical pulses with wavelengths straddling the visible range (400 and 800 nm) induce transient broad-band THz transparency in the MXene that persists for nanoseconds. We demonstrate that optically induced transient THz transparency is independent of temperature from 95 to 290 K. This discovery opens new possibilities for development of switchable electromagnetic interference shielding materials and devices that can be rendered partially transparent on demand for transmitting THz signals, or for designing new THz devices such as sensitive optically gated detectors.

Abstract-Equilibrium and non-equilibrium free carrier dynamics in two-dimensional Ti3C2Tx MXenes: THz spectroscopy study

Guangjiang Li, Kateryna Kushnir, Yongchang Dong, Sergii Chertopalov, Apparao M Rao, Vadym Mochalin, Ramakrishna Podila,  Lyubov Titova

http://iopscience.iop.org/article/10.1088/2053-1583/aacb9e/pdf


MXenes is an emerging class of two-dimensional transition metal carbides, nitrides and carbonitrides which exhibit large conductivity, ultrahigh volumetric capacitance, high threshold for light induced damage and nonlinear optical transmittance, making them attractive candidates for a variety of optoelectronic and electrochemical applications. Here, we report on equilibrium and non equilibrium free carrier dynamics of Ti3C2Tx gleaned from THz spectroscopic studies for the first time. Ti3C2TX showed high (~ 2x1021 cm-3) intrinsic charge carrier density and relatively high (~34 cm2/Vs) mobility of carriers with an exceptionally large, ~ 46,000 cm-1 absorption in the THz range, which suggests that Ti3C2Tx is well suited for THz detection. We also demonstrate that Ti3C2Tx conductivity and THz transmission can be manipulated by photoexcitation, as absorption of near-infrared, 800 nm pulses is found to cause transient suppression of the conductivity that recovers over hundreds of picoseconds. The possibility of control over THz transmission and conductivity by photoexcitation suggests the promise for application of Ti3C2Tx Mxenes in THz modulation devices and variable electromagnetic shielding.

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