Synergistic enhancement of thermoelectric performance in n-type Sb2Te3 alloyed PbTe via I/Ge co-doping

PbTe-based thermoelectric materials are promising for mid-temperature waste heat recovery, yet n-type PbTe underperforms its p-type counterpart. Herein, high-performance n-type PbTe is achieved through I/Ge co-doping and in-situ composite engineering with Sb 2 Te 3 prepared by melting combined spark plasma sintering. Sb 2 Te 3 alloying introduce in-situ formed Sb/Sb 2 Te 3 precipitates. Furthermore, iodine doping optimizes the carrier concentration to ∼3.4 × 10 19 cm –3 , boosting the room-temperature electrical conductivity to ∼1404 S cm −1 and yielding a high power factor of ∼17.4 μW cm −1 K −2 for the PbTe-Sb 2 Te 3 sample. Meanwhile, lattice thermal conductivity is synergistically suppressed to ∼0.37 W m –1 K –1 at 673 K through Ge-induced point defects/off-center anharmonicity and Sb/Sb 2 Te 3 precipitates. This synergistic strategy results in a peak ZT of ∼1.30 at 823 K and a high average ZT of ∼0.91 at 323–823 K. This work demonstrates that synergistic I/Ge co-doping and composite precipitation effectively enhance thermoelectric performance in n-type PbTe.