High-performance eco-friendly MnTe thermoelectrics through introducing SnTe nanocrystals and manipulating band structure

MnTe, which is comprised of earth-abundant and environmentally friendly elements, shows great potential for waste heat recovery in the moderate temperature range. However, its low carrier concentration limits its thermoelectric performance. Here, we achieved ultrahigh thermoelectric performance of MnTe by manipulating band structure and introducing SnTe nanocrystals. We found that incorporation of SnTe exerts a high band convergence in the electronic structure of MnTe, leading to remarkable enhancement of Seebeck coefficient. The Seebeck coefficient was greatly enhanced compared with previously reported doped MnTe. Furthermore, the carrier concentration can be optimized simultaneously by introducing SnTe. The large Seebeck coefficient combined with increased electrical conductivity give rise to high power factor ~1230 μWm−1 K−2. Meanwhile, SnTe nanocrystals help to achieve highly effective phonon scattering leading to markedly reduced lattice thermal conductivity. The proposed novel strategy decouples electron and phonon transport of MnTe, contributing to a record high ZT of ~1.4 at 873 K for the Mn1.06Te-2% SnTe material. Our finding promotes MnTe-based materials as a robust candidate for waste heat recovery at medium temperature.