We found that a high mobility semimetal 1T-MoTe2 shows a significant pressure-dependent change in the cryogenic thermopower in the vicinity of the critical pressure, where the polar structural transition disappears. With the application of a high pressure of 0.75 GPa, while the resistivity becomes as low as 10 {mu}{Omega}cm, thermopower reached the maximum value of 60 {mu}VK-1 at 25 K, leading to a giant thermoelectric power factor of 300 {mu}WK-2cm-1. Based on semiquantitative analyses, the origin of this behavior is discussed in terms of inelastic electron-phonon scattering enhanced by the softening of zone center phonon modes associated with the polar structural instability.
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