Temperature-dependent optical and electrical properties of bulk Ti2AlC and two-dimensional MXenes from first-principles

Abstract

The accurate representation of optical and electrical properties of MAX phase ternary carbide Ti2AlC and its derivative two-dimensional MXenes at finite temperature is crucial to render their applications in electrodes and photocatalysis. With the assumption of empirical electron scattering rate, however, previous works fails to accurately predict their optical and electrical properties. In this work, we start from calculating the electron-phonon interactions to accurately obtain electron scattering rate and then use them to obtain optical and electrical properties of Ti2AlC and two-dimensional MXenes from fully first-principles without empirical parameters. By combining the electron-phonon interaction with semiclassical Boltzmann transport theory, the electronic resistivity at finite temperature was calculated. And the dielectric function was computed by superimposing the intraband and interband transition, with the electron scattering rate obtained from solving electron-phonon coupling. The calculated resistivity and dielectric function of Ti2AlC were compared with available experimental results in literature, and demonstrate an overall good agreement. The calculated electrical and optical properties of MXenes show strong dependence on the surface terminated groups. When terminated with F or OH, the 2D MXenes shows metallic properties with good conducting ability, while Ti2CO2 exhibits semiconducting property. The results obtained from this work help to advance 2D MXenes in the applications such as transparent electrodes and photocatalysis.