Novel layered As2Ge with a pentagonal structure for potential thermoelectrics

Abstract

The versatile properties of two-dimensional materials indicate that they have enormous potential for applications in thermoelectrics. In this work, we proposed a novel layered pentagonal-structured As₂Ge crystal and investigated its stability and electronic structure using density functional theory (DFT) calculations. By combining the results of DFT with Boltzmann transport and phonon transport theory, we studied the electronic conductivity, thermal conductivity and thermoelectric transport properties. It was found that the As₂Ge monolayer is a stable layered semiconductor with a wide indirect band gap of 2.43 eV. It exhibits a high electron mobility of up to 7595 cm² V⁻¹ s⁻¹. The n-type monolayer of As₂Ge can achieve a remarkable ZT value as high as 4.36 at 1000 K, and the maximal value of ZT in p-type As₂Ge is predicted to reach 3.5 at 1000 K.