PAW-mediated ab initio simulations on linear response phonon dynamics of anisotropic black phosphorous monolayer for thermoelectric applications.

The first-order standard perturbation theory combined with ab initio projector augmented wave operator challenges the realization of the standard Sternheimer equation with linear computational efficiency. This efficiency motivates us to describe the electron-phonon interaction in a two-dimensional (2D) black phosphorous monolayer using generalized density functional perturbation theory (DFPT) with Boltzmann transport theory (BTE). Subsequently, linear response phonon dynamic behaviours in terms of conductivities, Seebeck coefficients and transport properties are studied for the thermoelectric application. The analysis reveals crystal orientation dependence via structural anisotropy and density of states of the monolayer structure. Momentum-dependent phonon population dynamics along with phonon linewidth are efficient in terms of reciprocal space electronic states. The optimized values of thermal conductivities of electrons and Seebeck coefficients act as driving forces to modulate thermoelectric effects. Figures of merit are calculated to be ∼0.074 at 300 K and ∼0.152 at 500 K of the MLBP system as a function of the power factor. The value of lattice thermal conductivity is 37.15 W m-1 K-1 at room temperature and follows inverse dependency with temperature. With the anticipated superior performance, profound thermoelectric applications can be achieved, particularly in the monolayer black phosphorous system.