Anisotropic transports, Thermoelectric properties, Crystal growth, InTe, First-principle calculations, Materials of engineering and construction. Mechanics of materials, TA401-492

InTe single crystals have demonstrated great promise in the field of thermoelectric materials, particularly when oriented along the [110] direction. This specific crystal orientation exhibits higher electronic conductivity and lower thermal conductivity compared to other orientations of InTe. Through first-principles calculations, we identified the anisotropic valence band and phonon dispersion as the underlying factors. Moreover, reducing the density of In+ vacancies in InTe was found to lower the band effective mass and modulate carrier scattering, enhancing the material quality factor (B). To explore these findings, we systematically grew InTe single crystals, achieving exceptional thermoelectric performance. A record-breaking power factor of 12.0 μW·cm−1·K−2 and a dimensionless figure of merit (zT) of 0.5 at room temperature were obtained. Notably, InTe crystals oriented along [110] with low In+ vacancy density exhibited the highest average zT of 0.63 among InTe-based thermoelectric materials within the 300–473 K temperature range. Furthermore, we introduced an effective method of reducing In+ vacancies through Indium vapor annealing, resulting in the highest reported carrier mobility of 182 cm2·V−1·s−1 for InTe. Our study highlights the potential for improving InTe's thermoelectric performance near room temperature through vacancy modulation and crystal orientation.