Density functional theory prediction on the excellent thermoelectric performance of AlP3 single-layer by As doping

Abstract The two-dimensional (2D) semiconductor AlP3 single-layer having similar structure to graphene exhibits higher thermoelectric (TE) power factor and lower lattice thermal conductivity, which is expected to be an excellent TE material. To further improve its TE performance, we obtained stable AlAsP2 and AlAs2P single-layers by doping As elements in AlP3 single-layer. By substitute arsenic atoms for phosphorus atoms, the TE conversion efficiency has been largely enhanced. Using first-principles calculation combined with the nonequilibrium Green function (NEGF) method and Landauer-Buttiker theory, we studied the electronic structures, the TE parameters and the anisotropy behavior of 2D AlAsnP3-n (n=0,1,2) single-layer. The calculation results showed that along the armchair direction the TE performance is superior to that along the zigzag direction, and the ZT values of AlAsnP3-n (n=0,1,2) single-layer by p-doping are larger than those by n-type doping. At 300 K, the armchair direction of AlAs2P single-layer has the highest ZT value 2.94. The doping of As atoms lead to a lower lattice thermal conductivity. This is because that the lower truncation frequency suppresses and softens the phonon mode, reducing the phonon group velocity. This study predicts potential application of AlAsnP3-n (n=0,1,2) single-layers in the field of TE conversion and provides a significant reference for the design of novel 2D TE devices.