Resonant energy level and ferromagnetic ordering lead to high average ZT in N-type PbSe thermoelectrics

Although electron spin can induce various magnetoelectric effects in carrier transport, its influence is typically weakened and overshadowed by phonon vibration under high temperature, and thus often overlooked in thermoelectric research. Here, we demonstrate a magnetic-ordering-based strategy to enhance thermoelectric performance in the diluted magnetic semiconductor MnSe-alloyed PbSe. We found that incorporating MnSe into Sb-doped PbSe generates resonant states near the Fermi level, resulting in a 20% increase in the Seebeck coefficient. Importantly, annealing homogenizes the Mn distribution and significantly strengthens ferromagnetic ordering within the matrix. The resulting ferromagnetism-mediated electroacoustic decoupling synergistically enhances the average power factor to 25 μW cm⁻¹ K⁻² and suppresses the lattice thermal conductivity to 0.7 W m⁻¹ K⁻¹. Consequently, a peak ZT of 1.6 at 700 K and an average ZT exceeding 1.0 across 300–800 K are achieved in the N-type PbSe system. Furthermore, single-leg device exhibits a conversion efficiency of 7% under a temperature difference of 480 K, surpassing mid-temperature performance benchmarks. This work establishes magnetic ordering as a pivotal and previously underexplored design parameter for realizing high-efficiency thermoelectric materials.