Origin of low thermal conductivity in monolayer PbI2

The mechanical, dynamical, and thermodynamic properties of monolayer PbI2 were investigated comprehensively via first-principles calculations. The generalized gradient approximation was chosen for exchange correlation effects. Thermodynamical properties, Debye temperature, sound velocity, charge density, Grneisen parameter, and thermal conductivity were examined in detail. The present elastic constants and phonon spectra have shown that PbI2 is stable both mechanically and dynamically. It was revealed that the relationship among atomic mass, interatomic bonds, phonon scattering, specific heat, sound velocities, Grneisen parameter, and Debye temperature cause low thermal conductivity. These results are matching with is predictions of Slack's theory.