Solid-State Cooling Based on TiSe₂ CDW Phase Transition

1T-TiSe₂ is a layered semimetal exhibiting CDW phase transition at T_CDW=200K. Bipolar transport of electrons and holes is evident in this material at above T_CDW and signifies itself in a slow increase in the thermal conductivity with temperature. Simultaneously, the Seebeck coefficient slowly decreases and transitions from electron-dominated transport (negative Seebeck) to hole-dominated transport (positive Seebeck). The resulting small gap opening at the phase transition corresponds to the strong temperature dependence of transport properties during phase change. As a result, we observe a large Thomson coefficient in this material with a peak of 450 μV/K and values larger than 150 μV/K over a 250K temperature range making this sample a potential candidate for Thomson cooling and heat management.