Most crystalline inorganic materials, except for metals and some layer materials, exhibit bad flexibility because of strong ionic or covalent bonds, while amorphous materials usually display poor electrical properties due to structural disorders. Here, we report the simultaneous realization of extraordinary room temperature flexibility and thermoelectric performance in Ag2Te1–xSx–based materials through amorphization. The coexistence of amorphous main phase and crystallites results in exceptional flexibility and ultralow lattice thermal conductivity. Furthermore, the flexible Ag2Te0.6S0.4 glass exhibits a degenerate semiconductor behavior with a room temperature Hall mobility of ~750 cm2 V−1 s−1 at a carrier concentration of 8.6 × 1018 cm−3, which is at least an order of magnitude higher than other amorphous materials, leading to a thermoelectric power factor also an order of magnitude higher than the best amorphous thermoelectric materials known. The in-plane prototype uni-leg thermoelectric generator made from this material demonstrates its potential for flexible thermoelectric device.

Half-Heusler and full-Heusler compounds were considered as independent phases with a natural composition gap. Here we report the discovery of TiRu1+xSb (x = 0.15 ~ 1.0) solid solution with wide homogeneity range and tunable p- to n-type semiconducting thermoelectrics, which bridges the composition gap between half- and full-Heusler phases. At the high-Ru end, strange glass-like thermal transport behavior with unusually low lattice thermal conductivity (~1.65 Wm−1K−1 at 340 K) is observed for TiRu1.8Sb, being the lowest among reported half-Heusler phases. In the composition range of 0.15 < x < 0.50, TiRu1+xSb shows abnormal semiconducting behaviors because tunning Ru composition results in band structure change and carrier-type variation simultaneously, which seemingly correlates with the localized d electrons. This work reveals the possibility of designing fascinating half-Heusler-like materials by manipulating the tetrahedral site occupancy, and also demonstrates the potential of tuning crystal and electronic structures simultaneously to realize intriguing physical properties.

Cubic half‐ and full‐Heusler compounds with respectively 18 and 24 valence electrons exhibit semiconducting behaviors according to the Slater–Pauling rule. In this work, a half‐Heusler‐like ZrRu1.5Sb semiconductor with the space group Ftrue4¯3m is discovered based on the Slater–Pauling rule. The ZrRu1.5Sb compound has 21 valence electrons per chemical formula and each atom has six valence electrons on average, showing a p‐type conduction with a dimensionless thermoelectric figure of merit zT ≈0.2 at 973 K. By adjusting the Ru content, both p‐type (x ≤ 0.5) and n‐type (x > 0.5) semiconductors are realized in the ZrRu1+xSb solid solution. Following this way, other half‐Heusler‐like semiconductors, such as ZrRu1.30Ni0.10Sb, ZrRu1.40Ni0.05Sb, and ZrRu1.30Ni0.05Sb, are also successfully designed and synthesized, demonstrating the effectiveness and practicality of our strategy to explore Slater–Pauling semiconductors. Furthermore, these half‐Heusler‐like semiconductors show promising potential as thermoelectric materials. The p‐type ZrRu1.4Sb and n‐type ZrRu1.7Sb samples have zT values of 0.38 at 973 K and 0.25 at 773 K, respectively, offering superior base materials for further optimizing their thermoelectric properties. The discovery of ZrRu1.5Sb‐based thermoelectric semiconductors demonstrates the great potential to design Slater–Pauling phases with exotic physical properties.

ZrCoSb is a promising p-type thermoelectric compound owing to its unique valence band structure, but the further improvement of its thermoelectric properties is constrained by less suitable dopants. In this work, we demonstrate that heavy element (ruthenium) doping at the 4c site allows simultaneous optimization of electrical transport properties and suppression of thermal conductivity. On the one hand, the replacement of Ru for Co results in valence band convergence by moving the Fermi level downward into the light Γ band, which significantly improves the electrical transport properties. On the other hand, the large difference in atomic size and mass between Ru and Co leads to strong strain field and mass fluctuation scattering, which remarkably reduces the lattice thermal conductivity. Consequently, a maximum thermoelectric figure of merit zT of 0.5 is achieved in ZrCo0.925Ru0.075Sb. This work highlights the promising effect of heavy-element doping at the 4c position on the thermoelectric performance of the p-type ZrCoSb compound.

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