Extraordinary thermoelectric performance in 2D group III monolayer XP <sub>3</sub> (X = Al, Ga, and In)
Xiaoheng Yang, Dan Han, Man Wang, Mu Du, Xinyu Wang
Abstract
Abstract Recently, two-dimensional (2D) group III monolayer XP 3 (X = Al, Ga, and In) have attracted great attention due to their excellent physical properties. We systematically investigate the thermoelectric (TE) properties of monolayer XP 3 by combining first-principles calculations and Boltzmann transport theory. It can be confirmed that monolayer XP 3 are dynamically stable structures and semiconductors with indirect band gaps. The carrier mobilities of monolayer XP 3 are calculated by using the deformation potential theory. Besides, at 300 K, the power factors of n -type doping AlP 3 , GaP 3 , and InP 3 are 35.51, 12.47, and 18.41 mW m −1 K −2 , respectively. Moreover, the phononic transport properties of all monolayers are evaluated, and lattice thermal conductivities of AlP 3 , GaP 3 , and InP 3 are 0.60, 4.47, and 1.93 W m −1 K −1 at 300 K, respectively, which can be explained by small phonon group velocity and ultra-low phonon lifetime. Finally, the outstanding TE figure of merits ( ZT ) of AlP 3 , GaP 3 , and InP 3 with n -type doping are 8.33, 2.09, and 4.22 at 700 K, respectively, which establishes a new record of TE performance of 2D materials. Our work clearly shows the prominent properties of novel 2D material XP 3 and will further promote technological development in the TE field.