Manipulating electronic properties of two-dimensional MXenes Cr2TiC2FCl by phonon vibration.

Although the manipulation of physical properties is common in applications of two-dimension (2D) materials, it is rare to tailor electronic properties by phonon vibration. In this article, we tailor the electronic band structure of Cr2TiC2FCl monolayer from indirect semiconducting state to metallic state by phonon modes ( A 1 2 , A 1 5 , and A 1 6 mode) with the Raman and infrared active. The A 1 4 mode makes Cr2TiC2FCl monolayer become direct semiconductor with a little gap, which can elevate the optical absorption efficiency of Cr2TiC2FCl monolayer, especially in the visible region. Meanwhile, both the conduction band minimum (CBM) and valence band maximum (VBM) are contributed by the spin-down channel; so, the electron hopping between VBM and CBM also does not need the participation of spin flipping and chiral phonon in Cr2TiC2FCl monolayer under the A 1 4 mode. These results are significant for the application of 2D materials in the semiconductor laser, solar cell, and photodetector.