Potential thermoelectric materials $\mathrm{CsMI_3}$ (M=Sn and Pb) in perovskite structures from the first-principles calculations

TL;DR

This study uses first-principles calculations to evaluate the thermoelectric properties of CsMI3 (M=Sn, Pb) perovskites, revealing their low thermal conductivity and promising ZT values for thermoelectric applications.

Contribution

First-principles calculations combined with Boltzmann transport theory to assess thermoelectric performance of CsMI3 perovskites, highlighting their potential as thermoelectric materials.

Findings

Low lattice thermal conductivities: 0.54 and 0.25 W/mK at room temperature.

Maximum ZT values of 0.63 and 0.64 at 1000 K for CsSnI3 and CsPbI3.

SOC significantly reduces n-type power factor, negligible effect on p-type.

Abstract

The thermoelectric properties of halide perovskites $\mathrm{CsMI_3}$ (M=Sn and Pb) are investigated from a combination of first-principles calculations and semiclassical Boltzmann transport theory by considering both the electron and phonon transport. The electronic part is performed using a modified Becke and Johnson (mBJ) exchange potential, including spin-orbit coupling (SOC), while the phonon part is computed using generalized gradient approximation (GGA). It is found that SOC has remarkable detrimental effect on n-type power factor, while has a negligible influence in p-type doping, which can be explained by considering SOC effect on conduction and valence bands. Calculated results show exceptionally low lattice thermal conductivities in $\mathrm{CsSnI_3}$ and $\mathrm{CsPbI_3}$, and the corresponding room-temperature lattice thermal conductivity is 0.54 $\mathrm{W m^{-1} K^{-1}}$ and 0.25 $\mathrm{W m^{-1} K^{-1}}$. At 1000 K, the maximal figure of merit $ZT$ is up to 0.63 and 0.64 for $\mathrm{CsSnI_3}$ and $\mathrm{CsPbI_3}$ with scattering time $\tau$=$10^{-14}$ s, and the peak $ZT$ is 0.49 and 0.41 with $\tau$=$10^{-15}$ s. These results make us believe that $\mathrm{CsMI_3}$ (M=Sn and Pb) in perovskite structures may be potential thermoelectric materials.