Antibonding p-d and s-p Hybridization Induce the Optimization of Thermal and Thermoelectric Performance of MGeTe₃ (M = In and Sb)

Abstract

Manipulation of phonon transport is the key to optimizing the overall energy conversion efficiency of thermoelectric materials. In this work, we demonstrate that the antibonding hybridization resulting from elemental substitution can weaken the interatomic interactions, which in turn enhances the structural anharmonicity and hinders the heat conduction of layered ABTe 3 (ABSe 3 ) (A = Al, Ga, In, As, and Sb; B = Si and Ge) compounds. It is revealed that the filled antibonded p-d state of GaSiTe 3 (GaSiSe 3 ) originates from the mixture of Ga-3d and Te-5p (Se-4p) orbitals, whereas the outer As-s electrons hybridize with the Te (Se)-p electrons to form antibonding states in AsSiTe 3 (AsSiSe 3 ). Consequently, the room temperature lattice thermal conductivity (κ L ) of AlGeTe 3 (AlGeSe 3 ) is reduced from 3.27 (3.86) W/mK to 0.62 (1.47) W/mK for GaSiTe 3 (GaSiSe 3 ) and 1.91 (1.74) W/mK for AsSiTe 3 (AsSiSe 3 ) in spite of their similar atomic masses and crystal structures. Based on these findings, we propose candidates of InGeTe 3 and SbGeTe 3 to realize potentially high thermoelectric performance by rationally incorporating heavy weight elements but still maintaining weak atomic binding interactions. Due to the low κ L of 0.26 (0.6) W/mK, a high n-type (p-type) ZT value of 2.18 (1.08) at 750 (650) K is finally captured in InGeTe 3 (SbGeTe 3 ). Our results not only provide insights to understand the relationship between chemical bonding and lattice thermal conductivity but also offer an approach to design and discover materials with expected thermal transport and thermoelectric properties.

Effect of Atomic Mass Contrast on Lattice Thermal Conductivity: A Case Study for Alkali Halides and Alkaline-Earth Chalcogenides

“…The development of modern computational approaches, along with rapid growth in high-performance computational architectures, makes it more routine to compute phonon transport properties of materials during the past decade. Extensive studies have been focused on exploring various mechanisms, namely, rattling, ,− lone-pair, − atomic mass, − bonding hierarchy, − , interplay among them, ,− , through sublattice alloying, , and designing principles have been proposed through chemical bonding. − to achieve low lattice thermal conductivity.…”

Lattice Dynamics and Thermal Transport in Semiconductors with Anti-Bonding Valence Bands

“…In this work, we focus on a chemical bonding signature: highest-occupied valence bands with a strong anti-bonding character in a semiconductor. Recent studies have suggested that anti-bonding chemical bonds are closely related to ultralow thermal conductivities in a range of materials. − The advantage of using the anti-bonding character of the highest-occupied valence band as a descriptor is that it can be efficiently analyzed using the crystal orbital Hamilton populations (COHP) method, , which only requires ground-state density functional theory (DFT) calculations. This method can be applied to any inorganic crystal structure and requires only basic structural and compositional information as input and minimal time and computing resources.…”

Remarkably Weakened Atomic Bonds from Dimeric Antibonding Hybridization and Enhanced Thermoelectric Performance of CdTe2

“…14 On the other hand, weakening the bonding strength through antibonding hybridization was identified as another effective method to improve heat transport. 15 For example, the intrinsically ultralow lattice thermal conductivity in CuBiI 4 can be attributed to the presence of robust p−d antibonding interactions between copper and iodine, which leads to the emergence of low-energy localized optical modes and suppresses the propagation of heat-carrying acoustic phonons. 16 Acharyya et al suggest that the presence of antibonding states weakens the bonds and induces soft elasticity, which, together with Cs rattling, results in an intrinsically ultralow κ L in all-inorganic halide perovskite Cs 3 Bi 2 I 9 .…”

“…Recently, significant advancements have been achieved in the exploration of TE candidates characterized by strong anharmonicity, such as SnSe, BiCuSeO, and Sb 2 Si 2 Te 6 . On the other hand, weakening the bonding strength through antibonding hybridization was identified as another effective method to improve heat transport . For example, the intrinsically ultralow lattice thermal conductivity in CuBiI 4 can be attributed to the presence of robust p–d antibonding interactions between copper and iodine, which leads to the emergence of low-energy localized optical modes and suppresses the propagation of heat-carrying acoustic phonons .…”