Manifestation of the thermoelectric properties in Ge-based halide perovskites

TL;DR

This study introduces Ge-based inorganic halide perovskites as promising thermoelectric materials with ultralow thermal conductivities and high carrier mobilities, offering a new avenue for efficient and cost-effective thermoelectric applications.

Contribution

It is the first to demonstrate that Ge-based halide perovskites possess exceptional thermoelectric properties, combining low thermal conductivity with high electrical mobility.

Findings

Thermal conductivity below 0.18 W/m·K

Carrier mobility above 860 cm²/V·s

Superior to conventional chalcogenide thermoelectrics

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 \ce{CsGeX3} (X = I, Br, 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 m$^{-1}$ K$^{-1}$ while very high carrier mobilities above 860 cm$^2$ V$^{-1}$ s$^{-1}$, 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.