Stable high-performance n-type PbTe enabled by lattice engineering for robust thermoelectric modules

P-type PbTe is one of the most representative high-performance thermoelectric materials, while the conversion efficiency of the fabricated module is limited by the relatively low zT of n-type PbTe. Here, we report the optimization of Cu-doped n-type PbTe by tuning the ionic migration energy, aiming for the high-efficiency and robust modules. It is revealed that the strategy of lattice contraction, achieved by Ge/Se co-doping, preserves the excellent carrier mobility from interstitial Cu and suppresses the unstable transport at high temperature. In the optimized sample of Pb 0.94 Ge 0.06 Cu 0.02 Se 0.04 Te 0.96 , a superior average zT (300–823 K) of 1.04 and a high peak zT of 1.45 at 823 K are obtained. A remarkable conversion efficiency of 10.5% at a temperature difference of 500 K is achieved in the fabricated PbTe-based module. • Ge/Se co-doping contracts the lattice, suppressing Cu migration and stabilizing n-type PbTe transport. • Optimized Pb 0.94 Ge 0.06 Cu 0.02 Se 0.04 Te 0.96 shows zT avg = 1.04 (300-823 K) and zT max = 1.45 at 823 K. • A seven-couple PbTe module using the optimized n-type leg reaches a record 10.5% efficiency at Δ T = 500 K..