Elucidating the role of lattice thermal conductivity in π‐phases of IV‐VI monochalcogenides for highly efficient thermoelectric performance

Abstract

Recently, an emerging new class of cubic π-polymorphs are being pursued as cost-effective and relatively less toxic materials for thermoelectric, photovoltaic, and optoelectronic applications. Using density functional formalism and semiclassical Boltzmann transport theory, we have systematically studied the thermoelectric performance of π-polymorphs. Hybrid functional (HSE03) is employed to realize accurate energy bandgaps, which helps to predict more accurate thermoelectric properties. The thermodynamic stability is observed by binding energies and phonon dispersions. It is observed that the Seebeck coefficients (S) are decreasing and electrical conductivities (σ) are increasing with carrier concentration. However, thermal conductivities are showing decreasing trends which lead to ultimately increased ZT. π-GeSe shows a high power factor $16.50 mW/mK 2 among all π-polymorphs. The figure of merit, ZT value, of π-SnS, π-SnSe, π-GeS, and π-GeSe are found to be 0.83, 1.20, 1.28, and 1.63 with optimal carrier concentration at 800 K. The present work highlights the potential of newly discovered cubic π-polymorphs of chalcogenides for highly efficient thermoelectric materials.

Metavalent Bonding Induced Phonon Transport Anomaly in 2D γ-MX (M = Ge, Sn, Pb; X = S, Se, Te) Monolayers

“…However, ZT can also be optimized by regulating the κ l , which relies only on lattice vibrations, atomic mass, and interatomic bonds. 1,2 Compounds with heavy constituent elements possess a low κ l 3,4 because increasing atomic mass flattens the phonon dispersion, low group velocity, and high phonon scattering rates. However, distinct anharmonic properties dominate over the reductive effect of atomic mass on κ l , thereby putting forward an alternate strategy.…”

Low lattice thermal conductivity and high figure of merit in n‐type doped full‐Heusler compounds X 2 YAu (X = Sr, Ba; Y = as, Sb)

“…TE materials have an important effect on solving the international energy shortage problem. [3][4][5] The conversion efficiency of TE materials is measured by the dimensionless figure of merit zT=S 2 σT= κ L þ κ E ð Þ, where S is Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, κ L and κ E are the thermal conductivity contributed by lattice and electrons respectively. 6,7 In addition, the power factor (PF) is also a crucial factor for forecast the TE properties, it can be expressed as S 2 σ.…”

“…Over these years, thermoelectric (TE) materials have received widespread attention, and the combination of thermal and electrical as well as semiconductor properties of TE materials make them useful for using heat to generate electricity. TE materials have an important effect on solving the international energy shortage problem 3‐5 …”