Enhanced Near‐Room‐Temperature Thermoelectric Properties of n‐Type PbSe and Cooling Device via Modulation Doping

Recently, PbSe has made significant progress in thermoelectric refrigeration. However, the optimization of the thermoelectric performance of polycrystalline PbSe is mostly concentrated at medium and high temperatures. Limited by the long growth cycle and poor mechanical processing strength of single crystals, it is extremely urgent to optimize the room‐temperature thermoelectric properties of polycrystalline PbSe. Here, the room‐temperature performance of polycrystalline n‐type PbSe‐based thermoelectric materials is optimized through the modulation doping strategy. The modulation doping strategy enhances the electrical conductivity by increasing the carrier mobility while maintaining a large Seebeck coefficient. The modulation doping is applied by incorporating high carrier concentration Pb 0.99875 (GaSb) 0.00125 Se into pristine PbSe. As a result, the n‐type polycrystalline [PbSe] 0.9 [Pb 0.99875 (GaSb) 0.00125 Se] 0.1 exhibits a high power factor of ∼34 µW cm −1 K −2 and a large dimensionless figure of merit of ∼0.6 at 300 K. Based on this, 18 pairs of thermoelectric cooling devices are fabricated using n‐type [PbSe] 0.9 [Pb 0.99875 (GaSb) 0.00125 Se] 0.1 and commercial p‐type Bi 0.5 Sb 1.5 Te 3 . The maximum cooling temperature difference of 45 K is obtained with a current of 2 A and the hot side temperature of 363 K. These findings have laid a solid foundation for promoting the application of polycrystalline PbSe materials in the field of thermoelectric cooling.