Thermoelectric transport in monolayer phosphorene

TL;DR

This paper models thermoelectric properties of monolayer phosphorene using a generalized Boltzmann approach, revealing anisotropic conductivity but nearly isotropic Seebeck coefficient and significant thermoelectric effects influenced by band coupling.

Contribution

It introduces a low-energy Hamiltonian for phosphorene and analyzes the impact of band coupling on thermoelectric properties, providing new insights into anisotropy and doping effects.

Findings

Conductivity is highly anisotropic, Seebeck coefficient nearly isotropic.

n-type conductivity is more affected by band coupling than p-type.

Thermoelectric effects are enhanced with thermopower sign change.

Abstract

We apply the generalized Boltzmann theory to describe thermoelectric transport properties of monolayer phosphorene in the presence of short- and long-range charged impurity interactions. First, we propose a low-energy Hamiltonian to explore the accurate electronic band structure of phosphorene in comparison with those results obtained by density-functional simulations. We explain the effect of the coupling between the conduction and valence bands on the thermoelectric properties. We show that the electric conductivity of phosphorene is highly anisotropic, while the Seebeck coefficient and figure of merit, without being influenced via either the presence or absence of the coupling term, are nearly isotropic. Furthermore, we demonstrate that the conductivity for the $n$ type of doping is more influenced by the coupling term than that of the $p$ type. Along with thermopower sign change, profound thermoelectric effects can be achieved.