Manifestation of the thermoelectric properties in Ge-based halide perovskites
Un-Gi Jong, Chol‐Jun Yu, Yun-Hyok Kye, Song‐Nam Hong, Hyon-Gyong Kim
Abstract
In spite of intensive studies on the chalcogenides as conventional thermoelectrics, it remains a challenge to find a proper material with high electrical but low thermal conductivities. In this work, we introduced a new class of thermoelectrics, Ge-based inorganic halide perovskites $\mathrm{CsGe}{X}_{3}$ $(X=\mathrm{I}, \mathrm{Br}, \mathrm{and} \mathrm{Cl})$, which were already known as a promising candidate for photovoltaic applications. By performing the lattice-dynamics calculations and solving the Boltzmann transport equation, we revealed that these perovskites have ultralow thermal conductivities below 0.18 W ${\mathrm{m}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$ while very high carrier mobilities above 860 ${\mathrm{cm}}^{2}\phantom{\rule{0.16em}{0ex}}{\mathrm{V}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$, being much superior to the conventional thermoelectrics of chalcogenides. These results highlight the way of searching high-performance and low-cost thermoelectrics based on inorganic halide perovskites.