In Situ Design of High‐Performance Dual‐Phase GeSe Thermoelectrics by Tailoring Chemical Bonds

Abstract

Composite engineering favors high thermoelectric performance by tuning the carrier and phonon transport. Herein, orthorhombic and rhombohedral dualphase GeSe are designed in situ by tailoring chemical bonds. Atom probe tomography verifies the coexistence of a covalently bonded orthorhombic phase and a metavalently bonded rhombohedral phase in GeSe-InTe alloys. The production of the rhombohedral phase simultaneously increases the carrier concentration, the carrier mobility, the band degeneracy, and the density-of-states effective mass due to the reduced formation energy of cation vacancies and the improved crystal symmetry. These attributes are beneficial to a high-power factor. In addition, the thermal conductivity can be significantly reduced due to the intrinsically strong lattice anharmonicity of the metavalently bonded phase, the interfacial acoustic phonon mismatch across different bonding mechanisms, and the phonon scattering at vacancy-solute clusters. Moreover, the metavalently bonded phase embraces higher solubility of dopants that enables the further optimization of properties by Cd-Ag doping, resulting in a zT of 0.95 at 773 K as well as enhanced strength and ductility in dual-phase Ge 0.94 Cd 0.03 Ag 0.03 Se(InTe) 0.15 . This work indicates that in situ design of dual-phase composites by tailoring chemical bonds is an effective method for enhancing the thermoelectric and mechanical properties of GeSe and other p-bonded chalcogenides.

Achieving Superior Thermoelectric Performance in Ge4Se3Te via Symmetry Manipulation with I–V–VI2 Alloying

“…Therefore, the low 𝜈 and strong anharmonicity contribute to the low 𝜅 lat for AgBiTe 2 -alloyed samples. Compared with the 𝜅 lat in previous reports, [26][27][28]31,[53][54][55] the 𝜅 lat of 0.25 W m −1 K −1 is the lowest value for GeSe-based materials (Figure 6c). [31] Ge 0.97 Pb 0.03 Se(InTe 3/2 ) 0.15 (GeSe-InTe 3/2 ), [28] Ge 0.94 Cd 0.03 Ag 0.03 Se(InTe) 0.15 (GeSe-InTe), [55] GeSe 0.55 Te 0.45 , [30] Ge 0.96 Bi 0.04 Se(MnCdTe 2 ) 0.10 (GeSe-MnCdTe 2 ), [26] and GeSe-0.2(AgSbTe 2 ); [27] (b) the comparison of PF avg values from 323 to 773 K with previous reports, including Ge 0.94 Cd 0.03 Ag 0.03 Se(InTe) 0.15 (GeSe-InTe), [55] Ge 0.97 Pb 0.03 Se(InTe 3/2 ) 0.15 (GeSe-InTe 3/2 ), [28] GeSe 0.55 Te 0.45 , [30] and Ge 0.9 Sb 0.08 Cd 0.02 Se 0.75 Te 0.25 (Ge(SbCd)SeTe).…”

“…Temperature-dependent a) total thermal conductivity, 𝜅 tot ; b) lattice thermal conductivity, 𝜅 lat ; and c) comparison of the temperature-dependent 𝜅 lat for x = 0.12 sample with previous reports, including (GeSe) 0.9 (AgBiTe 2 ) 0.1 , [53] GeAg 0.2 Sb 0.2 Se 1.4 , [54] GeSe-0.2(AgSbTe 2 ), [27] Ge 0.94 Cd 0.03 Ag 0.03 Se(InTe) 0.15 (GeSe-InTe), [55] Ge 0.9 Sb 0.08 Cd 0.02 Se 0.75 Te 0.25 (Ge(SbCd)SeTe), [31] Ge 0.96 Bi 0.04 Se(MnCdTe 2 ) 0.10 (GeSe-MnCdTe 2 ), [26] and Ge 0.97 Pb 0.03 Se(InTe 3/2 ) 0.15 (GeSe-InTe 3/2 ). [28] (GeSe-InTe), [55] Ge 0.97 Pb 0.03 Se(InTe 3/2 ) 0.15 (GeSe-InTe 3/2 ), [28] GeSe 0.55 Te 0.45 , [30] and Ge 0.9 Sb 0.08 Cd 0.02 Se 0.75 Te 0.25 (Ge(SbCd)SeTe). [31] hexagonal Ge 4 Se 3 Te, the rhombohedral Ge 4 Se 3 Te, and AgBiTe 2alloyed Ge 4 Se 3 Te rhombohedral phase were calculated (Figure 8).…”

Gibbs Adsorption and Zener Pinning Enable Mechanically Robust High‐Performance Bi2Te3‐Based Thermoelectric Devices

“…[ 1–4 ] The performance of a TE material is usually gauged by a dimensionless figure of merit (ZT), defined as $${\rm{ZT}} = {S}^2\sigma T/\kappa $$, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and κ is the total thermal conductivity contributed by the lattice vibration κ lat and the carrier transport κ e . [ 5 ] Boosting ZT is still the leading goal for TE research, which can be realized by various strategies such as band engineering, [ 6–8 ] microstructural engineering, [ 5,9–13 ] chemical bonding engineering, [ 14–15 ] and grain boundary (GB) engineering. [ 16–18 ] Owing to the solid‐state working principle, TE technologies can be utilized for cooling DNA synthesizers, semiconductor lasers, microprocessors, and low‐wattage power generators.…”

Exceptional Thermoelectric Performance of Cu2(Zn,Fe,Cd)SnS4 Thin Films

“…In the present work, the total thermal conductivity κ tot of the CZFCTS-1 thin films was determined by TFA. The electronic thermal conductivity κ ele was calculated from the electrical transport measurements using the Wiedemann–Franz Law as (eq ) κ ele = L σ T where the Lorenz number L was estimated using eq L = ( 1.5 + exp true[ prefix− false| S false| 116 true] ) × 10 − 8 0.25em V 2 0.25em K − 2 …”

“…In the present work, the total thermal conductivity κ tot of the CZFCTS-1 thin films was determined by TFA. The electronic thermal conductivity κ ele was calculated from the electrical transport measurements using the Wiedemann−Franz Law as (eq 2) 65 L T ele =…”