Large Mobility Enables Higher Thermoelectric Cooling and Power Generation Performance in n-type AgPb₁₈₊SbTe₂₀...

The room-temperature thermoelectric performance of materials underpins their thermoelectric cooling ability. Carrier mobility plays a significant role in the electronic transport property of materials, especially near room temperature, which can be optimized by proper composition control and growing crystals. Here, we grow Pb-compensated AgPb₁₈₊SbTe₂₀ crystals using a vertical Bridgman method. A large weighted mobility of ∼410 cm² V^-1 s^-1 is achieved in the AgPb_18.4SbTe₂₀ crystal, which is almost 4 times higher than that of the polycrystalline counterpart due to the elimination of grain boundaries and Ag-rich dislocations verified by atom probe tomography, highlighting the significant benefit of growing crystals for low-temperature thermoelectrics. Due to the largely promoted weighted mobility, we achieve a high power factor of ∼37.8 μW cm^-1 K^-2 and a large figure of merit ZT of ∼0.6 in AgPb_18.4SbTe₂₀ crystal at 303 K. We further designed a 7-pair thermoelectric module using this n-type crystal and a commercial p-type (Bi, Sb)₂Te₃-based material. As a result, a high cooling temperature difference (ΔT) of ∼42.7 K and a power generation efficiency of ∼3.7% are achieved, revealing promising thermoelectric applications for PbTe-based materials near room temperature.